inital commit

25 files changed, 1272 insertions, 0 deletions

diff --git a/1.13.c b/1.13.c
new file mode 100644
index 0000000..3981496
--- /dev/null
+++ b/1.13.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#define MAX_LEN 10
+
+// Programm to produce histogram based on the length of words
+
+int
+main()
+{
+  int i, j, input, word_len, big_words;
+  int len[MAX_LEN];
+
+  word_len = big_words = 0;
+  for (i = 0; i< MAX_LEN; i++)
+    len[i]=0;
+
+  while ((input = getchar()) != EOF) {
+    if(input == ' ' || input == '\n' || input == '\t') {
+      if (word_len >= MAX_LEN)
+        big_words++;
+      else
+        len[word_len]++;
+      word_len = 0;
+    }
+    else 
+      word_len++;
+  }
+
+  if(input != ' ' && input != '\n' && input != '\t') {
+    if (word_len >= MAX_LEN)
+        big_words++;
+      else
+        len[word_len]++;
+  }
+
+  printf("\n");
+
+  for (i = 0; i< MAX_LEN; i++) {
+    printf(" %d -- %3d: ", i, len[i]);
+    for (j =0; j < len[i]; j++)
+      printf("*");
+    printf("\n");
+  }
+
+  printf(">%d -- %3d: ", (MAX_LEN-1), big_words);
+  for (j =0; j < big_words; j++)
+      printf("*");
+  printf("\n");
+}
+
diff --git a/1.14.c b/1.14.c
new file mode 100644
index 0000000..8274008
--- /dev/null
+++ b/1.14.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#define MAX_CHAR 128 // ASCII set
+
+int t0;
+
+/* program to print a histogram of the frequencies of diffrent 
+ * characters in its input */
+
+int t1;
+
+// this is a test1
+
+int t2;
+
+/* trrrrrr2 */
+
+int 
+main(void)
+{
+  int i, j, input;
+  int char_count[MAX_CHAR];
+
+  for (i = 0; i < MAX_CHAR; i++)
+    char_count[i] = 0;
+
+  while((input = getchar()) != EOF) {
+    char_count[input]++;
+  }
+
+  printf("\n");
+
+  for (i =0; i < MAX_CHAR; i++) {
+    if (char_count[i] == 0)
+      continue;
+
+    if (i == '\t')
+      printf(" \\t -- %3d: ", char_count[i]);
+    else if (i == '\n')
+      printf(" \\n -- %3d: ", char_count[i]);
+    else if (i == ' ')
+      printf("' ' -- %3d: ", char_count[i]);
+    else
+      printf("  %c -- %3d: ", i, char_count[i]);
+
+    for (j = 0; j <= char_count[i]; j++)
+      printf("*");
+    printf("\n");
+  }
+}
diff --git a/1.15.c b/1.15.c
new file mode 100644
index 0000000..9e1b8dd
--- /dev/null
+++ b/1.15.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+
+#define TRUE 1
+
+float conv_temp(int temp_c);
+
+int 
+main(void)
+{
+  int input, temp_c;
+  while(TRUE) {
+    printf("Enter temp in C: ");
+    scanf("%d", &temp_c);
+    printf("%d C is %.1f F\n", temp_c, conv_temp(temp_c));
+  }
+
+  return 0;
+}
+
+float 
+conv_temp(int temp_c)
+{
+  return (9.0/5.0 * temp_c) + 32.0;
+}
diff --git a/1.16.c b/1.16.c
new file mode 100644
index 0000000..12c9600
--- /dev/null
+++ b/1.16.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+
+#define MAXLINE 1000
+
+int gline(char str[], int len);
+void cp_str(char to[], char from[]);
+
+int 
+main(void)
+{
+  int len, max;
+  char str[MAXLINE];
+  char mstr[MAXLINE];
+
+  max = 0;
+
+  while ((len = gline(str, MAXLINE)) > 0)
+    if (len > max) {
+      cp_str(mstr, str);
+      max = len;
+    }
+
+  if (max > 0)
+    printf("\nlength: %d\n%s", max, mstr);
+
+  return 0;
+}
+
+int 
+gline(char str[], int len)
+{
+  int i;
+  char input;
+  for (i = 0; i < len-1 && (input = getchar()) != EOF && input != '\n'; i++)
+    str[i] = input;
+
+  if (input == '\n' && i < len-1) {
+    str[i] = '\n';
+    ++i;
+  }
+  
+  str[i] = '\0';
+
+    return i;
+}
+
+void
+cp_str(char to[], char from[])
+{
+  for(int i =0; (to[i] = from[i]) != '\0'; i++)
+    ;
+}
diff --git a/1.17.c b/1.17.c
new file mode 100644
index 0000000..5fca79c
--- /dev/null
+++ b/1.17.c
@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+#define MAXLINE 1000
+
+int gline(char str[], int len);
+
+int 
+main(void)
+{
+  int len;
+  char str[MAXLINE];
+
+  while ((len = gline(str, MAXLINE)) > 0)
+    if (len > 80)
+      printf("\nlength: %d\n%s\n", len, str);
+
+  return 0;
+}
+
+int 
+gline(char str[], int len)
+{
+  int i;
+  char input;
+  for (i = 0; i < len-1 && (input = getchar()) != EOF && input != '\n'; i++)
+    str[i] = input;
+
+  if (input == '\n' && i < len-1) {
+    str[i] = '\n';
+    ++i;
+  }
+  
+  str[i] = '\0';
+
+    return i;
+}
diff --git a/1.18.c b/1.18.c
new file mode 100644
index 0000000..36f5ad9
--- /dev/null
+++ b/1.18.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+
+#define MAXLINE 1000
+
+int 
+main(void)
+{
+  int input, i, non_blank;
+  char str[MAXLINE];
+
+  i = 0;
+  non_blank = -1;
+
+  while ((input = getchar()) != EOF) {
+    while (input != '\n' && input != EOF) {
+      str[i] = input;
+
+      if (input != ' ' && input != '\t')
+        non_blank = i;
+
+      ++i;
+      input = getchar();
+    }
+
+    if (non_blank == -1)
+      continue;
+
+    str[non_blank+1] = '\0';
+    printf("%s\n", str);
+    
+    i = 0;
+  }
+
+  return 0;
+}
diff --git a/1.19.c b/1.19.c
new file mode 100644
index 0000000..c156afe
--- /dev/null
+++ b/1.19.c
@@ -0,0 +1,70 @@
+#include <stdio.h>
+
+#define MAXLINE 1000
+
+void reverse(char str[]);
+void str_cp(char to[], char from[]);
+
+int
+main(void)
+{
+	int input, i;
+	char str[MAXLINE];
+
+	i = 0;
+
+	while ((input = getchar()) != EOF) {
+		str[i] = input;
+		i++;
+
+		if (input == '\n') {
+                        str[i] = '\0';
+			i = 0;
+			reverse(str);
+                        printf("%s\n", str);
+		}
+	}
+
+	return 0;
+}
+
+void 
+str_cp(char to[], char from[])
+{
+	int i, last_non_blank;
+
+        last_non_blank = -1;
+
+	for (i = 0; from[i] != '\0'; ++i) {
+          if (from[i] != ' '&& from[i] != '\n' && from[i] != '\t')
+            last_non_blank = i;
+
+          to[i] = from[i];
+        }
+		
+        if (last_non_blank >= 0)
+          to[last_non_blank+1] = '\0';
+        else
+          to[i] = '\0';
+}
+
+void
+reverse(char str[])
+{
+	int i, len;
+	char storage[MAXLINE];
+
+        i = len = 0;
+
+	str_cp (storage, str);
+	
+	for ( len = 0; storage[len] != '\0'; len++)
+		;
+
+	for ( i = 0; i < len; ++i)
+		str[i] = storage[len-1-i];
+
+	str[i] = '\0';
+}
+
+	
diff --git a/1.20.c b/1.20.c
new file mode 100644
index 0000000..2606fa1
--- /dev/null
+++ b/1.20.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+
+#define TAB 8
+
+int 
+main(void)
+{
+  int input, count, space;
+
+  count = 0;
+
+  while ((input = getchar()) != EOF) {
+    if (input == '\t') {
+      space = (TAB - (count % TAB));
+
+      for (space = (TAB - (count % TAB)); space > 0; space--) {
+        printf(" ");
+        count++;
+      }
+    }
+
+    else if (input == '\n')
+      count = 0;
+
+    else {
+      count++;
+      printf("%c", input);
+    }
+  }
+
+  return 0;
+}
diff --git a/1.21.c b/1.21.c
new file mode 100644
index 0000000..d7f7a27
--- /dev/null
+++ b/1.21.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#define TAB 8
+
+int 
+main(void)
+{
+  int count, tab, blank;
+  char input;
+
+  count = 0;
+
+  while((input = getchar()) != EOF) {
+    
+    if (input == ' ')
+      count++;
+
+    else {
+
+      if (count > 0) {
+        for (tab = count/TAB; tab > 0; --tab)
+          printf("\t");
+        for (blank = count%TAB; blank > 0; --blank)
+          printf(" ");
+      }
+      count = 0;
+
+      printf("%c", input);
+    }
+  }
+
+  return 0;
+}
diff --git a/1.22.c b/1.22.c
new file mode 100644
index 0000000..12d7784
--- /dev/null
+++ b/1.22.c
@@ -0,0 +1,31 @@
+#include <stdio.h>
+
+#define LINE_LENGTH 230
+#define TAB 8
+
+int 
+main(void)
+{
+  int count;
+  char input;
+
+  count = 0;
+  
+  while ((input = getchar()) != EOF) {
+    if (input == '\n')
+      count = 0;
+    else if (input == '\t')
+      count = count + TAB;
+    else 
+      count++;
+
+    printf("%c", input);
+
+    if (count >= LINE_LENGTH) {
+      printf("\n");
+      count = 0;
+    }
+  }
+
+  return 0;
+}
diff --git a/1.23.c b/1.23.c
new file mode 100644
index 0000000..e2f2f5f
--- /dev/null
+++ b/1.23.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+
+#define OUT 0
+#define STAR 1
+#define SLASH 2
+
+/* this is a c programm to remove all comments from c programms */
+// including "slash comments" 
+/* and "star comments" */
+// without the use of arrays
+
+int 
+main(void)
+{
+  char input, temp;
+  int state;
+
+  state = OUT;
+
+  while ((input = getchar()) != EOF) {
+
+    if (input == '/') {
+       temp = input;
+
+      if ((input = getchar()) == '*')
+        state = STAR;
+      else if (input == '/')
+        state = SLASH;
+      else 
+        printf("%c", temp);
+
+    }
+
+    else if (input == '*' && state == STAR) {
+
+      if ((input = getchar()) == '/') {
+        state = OUT;
+
+        if ((input = getchar()) != '\n')
+          printf("%c", input);
+
+        continue;
+      }  
+    }
+
+    else if (input == '\n' && state == SLASH) {
+      state = OUT;
+      continue;
+    }
+
+    if (state == OUT)
+      printf("%c", input);
+  }
+
+  return 0;
+}
diff --git a/1.24.c b/1.24.c
new file mode 100644
index 0000000..5e24942
--- /dev/null
+++ b/1.24.c
@@ -0,0 +1,161 @@
+#include <stdio.h>
+
+#define OUT 0
+#define FALSE -1
+#define TRUE 1
+#define STAR 1
+#define SLASH 2
+
+void count(char input, int* parentheses, int* brackets, int* braces);
+
+/* this is a c programm to detect syntax errors in c programms */
+
+int 
+main(void)
+{
+  char input;
+  int temp, state, line, parentheses, brackets, braces, single_quotes, double_quotes, double_quotes_line;
+
+  state = OUT;
+  parentheses = brackets = braces = single_quotes = double_quotes = double_quotes_line = 0;
+  line = 1;
+
+  while ((input = getchar()) != EOF) {
+
+    if (input == '\n') {
+      line++;
+      continue;
+    }
+
+    /* filiter out comments */
+
+    else if (input == '/') {
+       temp = input;
+
+      if ((input = getchar()) == '*') {
+        state = STAR;
+        temp = FALSE;
+      } 
+
+      else if (input == '/') {
+        state = SLASH;
+        temp = FALSE;
+      }
+
+    }
+
+    else if (input == '*' && state == STAR) {
+
+      if ((input = getchar()) == '/') {
+        state = OUT;
+        continue;
+      }  
+
+    }
+
+    else if (input == '\n' && state == SLASH) {
+      state = OUT;
+      continue;
+    }
+
+    if (temp != FALSE)
+      count(temp, &parentheses, &brackets, &braces);
+
+    if (state == OUT) {
+
+      if (input == '"' && double_quotes == TRUE) {
+        double_quotes = FALSE;
+        continue;
+      } 
+
+      /* process escape sequences  */
+
+      else if (input == '\\') {
+        input = getchar();
+
+        if (input == '\n') {
+          line++;
+          continue;
+        }
+
+        if (input != 'a' && input != 'b' && input != 'f' && input != 'n' && input != 'r' &&
+            input != 't' && input != 'v' && input != '\\' && input != '\'' && input != '"' && input != '?' && input != '0')
+          printf("unproper escape sequence detected at line %d\n", line);
+        
+        else if (input == 'o') {
+          if((input = getchar()) != 'o' || (input = getchar()) != 'o')
+            printf("unproper escape sequence detected at line %d\n", line);
+        }
+
+        else if (input == 'x') {
+          if((input = getchar()) != 'h' || (input = getchar()) != 'h')
+            printf("unproper escape sequence detected at line %d\n", line);
+        }
+
+        else 
+          continue;
+      }
+
+      /* process double quotes */
+
+      else if (input == '"') {
+        double_quotes = TRUE;
+        double_quotes_line = line;
+      }
+
+      /* process single quotes */ 
+
+      else if (input == '\'' && double_quotes != TRUE) {
+        ;
+        if ((input = getchar()) == '\\') {
+          input = getchar();
+        }
+
+        if ((input = getchar()) != '\'')
+          printf("unproper single quotes detected at line %d\n", line);
+
+        continue;
+      }
+
+      /* process all others */
+
+      count(input, &parentheses, &brackets, &braces);
+    }
+  }
+  
+  if (parentheses%=2)
+    printf("unproper parentheses detected\n");
+  if (brackets%=2)
+    printf("unproper brackets detected\n");
+  if (braces%=2)
+    printf("unproper braces detected\n");
+  if (double_quotes == TRUE)
+    printf("unproper double quotes detected at line %d\n", double_quotes_line);
+
+  return 0;
+}
+
+void 
+count(char input, int* parentheses, int* brackets, int* braces)
+{
+  switch (input) {
+        case '(' :
+          (*parentheses)++;
+          break;
+        case ')' :
+          (*parentheses)--;
+          break;
+        case '[' :
+          (*brackets)++;
+          break;
+        case ']' :
+          (*brackets)--;
+          break;
+        case '{' :
+          (*braces)++;
+          break;
+        case '}' :
+          (*braces)--;
+          break;
+  }
+}
diff --git a/2.1.c b/2.1.c
new file mode 100644
index 0000000..d029e84
--- /dev/null
+++ b/2.1.c
@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <limits.h>
+#include <float.h>
+
+int 
+main(void)
+{
+  unsigned char c;
+  unsigned short s;
+  unsigned int i;
+  unsigned long l;
+
+  c = ~0;
+  s = ~0;
+  i = ~0;
+  l = ~0;
+
+  c >>= 1;
+  s >>= 1;
+  i >>= 1;
+  l >>= 1;
+
+  /* signed values */
+
+  printf("limits char   min: %20d, max: %20d\n", CHAR_MIN, CHAR_MAX);
+  printf("comput char   min: %20d, max: %20d\n", -c-1, c);
+
+  printf("limits short  min: %20d, max: %20d\n", SHRT_MIN, SHRT_MAX);
+  printf("comput short  min: %20d, max: %20d\n", -s-1, s);
+
+  printf("limits int    min: %20d, max: %20d\n", INT_MIN, INT_MAX);
+  printf("comput int    min: %20d, max: %20d\n", -i-1, i);
+
+  printf("limits long   min: %20ld, max: %20ld\n", LONG_MIN, LONG_MAX);
+  printf("comput long   min: %20ld, max: %20ld\n", -l-1, l);
+
+  printf("limits float  min: %20g, max: %20g\n", FLT_MIN, FLT_MAX);
+  printf("limits double min: %20g, max: %20g\n", DBL_MIN, DBL_MAX);
+
+  /* unsigned values */
+
+  printf("limits uchar  min: %20d, max: %20u\n", 0, UCHAR_MAX);
+  printf("comput uchar  min: %20d, max: %20u\n", 0, c*2+1);
+
+  printf("limits ushort min: %20d, max: %20u\n", 0, USHRT_MAX);
+  printf("comput ushort min: %20d, max: %20u\n", 0, s*2+1);
+
+  printf("limits uint   min: %20d, max: %20u\n", 0, UINT_MAX);
+  printf("comput uint   min: %20d, max: %20u\n", 0, i*2+1);
+
+  printf("limits ulong  min: %20d, max: %20lu\n", 0, ULONG_MAX);
+  printf("comput ulong  min: %20d, max: %20lu\n", 0, l*2+1);
+
+  return 0;
+}
diff --git a/2.10.c b/2.10.c
new file mode 100644
index 0000000..edbf440
--- /dev/null
+++ b/2.10.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+
+char lower(char intput);
+
+int 
+main(void)
+{
+  char intput;
+
+  while((intput = getchar()) != EOF)
+    printf("%c", lower(intput));
+
+  return 0;
+}
+
+char 
+lower(char intput)
+{
+  return (intput >= 'A' && intput <= 'Z') ? intput-'A'+'a' : intput;
+}
diff --git a/2.2.c b/2.2.c
new file mode 100644
index 0000000..4e3f71a
--- /dev/null
+++ b/2.2.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+
+#define MAXLINE 1000
+
+int gline(char str[], int len);
+void cp_str(char to[], char from[]);
+
+int 
+main(void)
+{
+  int len, max;
+  char str[MAXLINE];
+  char mstr[MAXLINE];
+
+  max = 0;
+
+  while ((len = gline(str, MAXLINE)) > 0)
+    if (len > max) {
+      cp_str(mstr, str);
+      max = len;
+    }
+
+  if (max > 0)
+    printf("\nlength: %d\n%s", max, mstr);
+
+  return 0;
+}
+
+int 
+gline(char str[], int len)
+{
+  int i;
+  char input;
+
+  i = 0;
+
+  while (i < len-1) {
+    input = getchar();
+
+    if (input == EOF)
+      break;
+    else if (input == '\n')
+      break;
+
+    str[i] = input;
+    i++;
+  }
+    
+
+  if (input == '\n' && i < len-1) {
+    str[i] = '\n';
+    ++i;
+  }
+  
+  str[i] = '\0';
+
+    return i;
+}
+
+void
+cp_str(char to[], char from[])
+{
+  for(int i =0; (to[i] = from[i]) != '\0'; i++)
+    ;
+}
diff --git a/2.3.c b/2.3.c
new file mode 100644
index 0000000..21b0040
--- /dev/null
+++ b/2.3.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+
+int 
+main(void)
+{
+  char input;
+  int num;
+
+  num = 0;
+  
+  while ((input = getchar()) != EOF) {
+
+    if (input == '0') {
+      if ((input = getchar()) == 'x' || input == 'X')
+        continue;
+      else 
+        input = '0';
+    }
+
+    if (!((input >= '0' && input <= '9') || (input >= 'a' && input <= 'f') || (input >= 'A' && input <= 'F')))
+      continue;
+    else if (input >= '0' && input <= '9')
+      num = num * 16 + input - '0';
+    else if (input >= 'a' && input <= 'f')
+      num = num * 16 + 10 + input - 'a';
+    else if (input >= 'A' && input <= 'F')
+      num = num * 16 + 10 + input - 'A';
+
+  }
+
+  printf("\n%d\n", num);
+
+  return 0;
+}
diff --git a/2.4.c b/2.4.c
new file mode 100644
index 0000000..e195a09
--- /dev/null
+++ b/2.4.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+
+/* function to delete  each character in str1 that matches with str2 */
+char* squeeze(char str[], const char cs[]);
+
+int 
+main(void)
+{
+  char str[] = "ok chud you win this time";
+  char del[] = "oi";
+
+  printf("%s\n", squeeze(str, del));
+
+  return 0;
+}
+
+char*
+squeeze(char str[], const char cs[])
+{
+  int i, j, k;
+
+  for (i = j = 0; str[i] != '\0'; i++) {
+
+    for (k = 0; cs[k] != '\0'; k++)
+      if (str[i] == cs[k])
+        break;
+
+    if (cs[k] == '\0')
+      str[j++] = str[i];
+  }
+
+  str[j] = '\0';
+
+  return str;
+}
diff --git a/2.5.c b/2.5.c
new file mode 100644
index 0000000..6988cfb
--- /dev/null
+++ b/2.5.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+
+/* function to delete  each character in str1 that matches with str2 */
+int any(const char s1[], const char s2[]);
+
+int 
+main(void)
+{
+  char str[] = "ok chud you win this time";
+  char del[] = "ic";
+
+  printf("%d\n", any(str, del));
+
+  return 0;
+}
+
+int 
+any(const char s1[], const char s2[])
+{
+  int i, j;
+
+  for (i = 0; s1[i] != '\0'; i++) {
+
+    for (j = 0; s2[j] != '\0'; j++)
+      if (s2[j] == s1[i])
+        return i+1;
+
+  }
+
+  return -1;
+}
+
diff --git a/2.6.c b/2.6.c
new file mode 100644
index 0000000..23ce1e6
--- /dev/null
+++ b/2.6.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+
+#define INT_NBITS 32
+
+unsigned getbits(unsigned x, int from, int to);
+void pbits(int x);
+unsigned setbits(unsigned x, int from, int to, int source);
+
+int 
+main(void)
+{
+  int x = 423834583;
+  int y = 354543434;
+
+  pbits(x);
+  pbits(y);
+
+  pbits(setbits(x, 12, 5, y));
+  
+  return 0;
+}
+
+unsigned 
+getbits(unsigned x, int from, int to)
+{
+  return (x >> (from+1-to)) & ~(~(unsigned)0 << to);
+}
+
+void 
+pbits(int x)
+{
+  for (int i = INT_NBITS-1; i >= 0; i--) {
+    if (i%4 == 3)
+      printf(" ");
+
+    printf("%u", getbits(x, i, 1));
+  }
+
+  printf("\n");
+}
+
+unsigned 
+setbits(unsigned x, int from, int to, int source)
+{
+  int model = ((((unsigned)~0 << (INT_NBITS-from)) >> (INT_NBITS - (from+to))) << to);
+  return (x & ~model) | (source & model);
+}
diff --git a/2.7.c b/2.7.c
new file mode 100644
index 0000000..fc493aa
--- /dev/null
+++ b/2.7.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+
+#define INT_NBITS 32
+
+unsigned getbits(unsigned x, int from, int to);
+void pbits(int x);
+unsigned invert(unsigned x, int from, int to);
+
+int 
+main(void)
+{
+  int x = 3423834583;
+
+  pbits(x);
+
+  pbits(invert(x, 32, 32));
+  
+  return 0;
+}
+
+unsigned 
+getbits(unsigned x, int from, int to)
+{
+  return (x >> (from+1-to)) & ~(~(unsigned)0 << to);
+}
+
+void 
+pbits(int x)
+{
+  for (int i = INT_NBITS-1; i >= 0; i--) {
+    if (i%4 == 3)
+      printf(" ");
+
+    printf("%u", getbits(x, i, 1));
+  }
+
+  printf("\n");
+}
+
+unsigned 
+invert(unsigned x, int from, int to)
+{
+  return x ^ ((((unsigned)~0 << (INT_NBITS-from)) >> (INT_NBITS-to)) << (from-to));
+}
diff --git a/2.8.c b/2.8.c
new file mode 100644
index 0000000..8f3ecbf
--- /dev/null
+++ b/2.8.c
@@ -0,0 +1,55 @@
+#include <stdio.h>
+
+#define INT_NBITS 32
+#define ONE 1
+
+unsigned getbits(unsigned x, int from, int to);
+void pbits(int x);
+unsigned rightrot(unsigned x, int n);
+
+int 
+main(void)
+{
+  int x = 2394234;
+
+  pbits(x);
+
+  pbits(rightrot(x, 8));
+  
+  return 0;
+}
+
+unsigned 
+getbits(unsigned x, int from, int to)
+{
+  return (x >> (from+1-to)) & ~(~(unsigned)0 << to);
+}
+
+void 
+pbits(int x)
+{
+  for (int i = INT_NBITS-1; i >= 0; i--) {
+    if (i%4 == 3)
+      printf(" ");
+
+    printf("%u", getbits(x, i, 1));
+  }
+
+  printf("\n");
+}
+
+unsigned 
+rightrot(unsigned x, int n)
+{
+  int model = (x >> n) << n;
+  for (int i = 1; i <= n; i++) {
+    int shift = n+1-i*2;
+
+    if (shift >= 0)
+      model |= ((x & (ONE << (n-i))) >> shift);
+    else
+      model |= ((x & (ONE << (n-i))) << -shift);
+  }
+
+  return model;
+}
diff --git a/2.9.c b/2.9.c
new file mode 100644
index 0000000..5a0ceb9
--- /dev/null
+++ b/2.9.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+int bitcount(unsigned num);
+
+int 
+main(void)
+{
+  int x = 1337; /* a random int */
+  printf("%d\n", bitcount(x));;
+
+  return 0;
+}
+
+int 
+bitcount(unsigned num)
+{
+  int bits;
+
+  for (bits = 0; num != 0; num &= (num-1))
+    bits++;
+
+  return bits;
+}
diff --git a/3.1.c b/3.1.c
new file mode 100644
index 0000000..25e2ca1
--- /dev/null
+++ b/3.1.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+
+int binsearch(int x, int v[], int n);
+int binsearch2(int x, int v[], int n);
+
+int 
+main(void)
+{
+  int v[10]= {1, 2, 3, 4, 5, 6, 7, 8, 9, 11};
+  printf("%d\n", binsearch(v[5], v, 10));
+}
+
+int 
+binsearch(int x, int v[], int n) 
+{
+  int low, high, mid;
+
+  low = 0;
+  high = n-1;
+
+  while (low <= high) {
+    mid = (low+high)/2;
+
+    if (x < v[mid])
+      high = mid - 1;
+    else if (x > v[mid])
+      low  = mid + 1;
+    else 
+      return mid;
+  }
+
+  return -1;
+}
+
+int 
+binsearch2(int x, int v[], int n) 
+{
+  int low, high, mid;
+
+  low = 0;
+  high = n-1;
+
+  while (low < high) {
+    mid = (low+high)/2;
+
+    if (x <= v[mid])
+      high = mid;
+    else 
+      low = mid+1;
+
+  }
+
+  /* here low == high */
+  
+  return (x == v[low]) ? low : -1; 
+}
diff --git a/3.2.c b/3.2.c
new file mode 100644
index 0000000..57aef6c
--- /dev/null
+++ b/3.2.c
@@ -0,0 +1,119 @@
+#include <stdio.h>
+
+#define MAXLEN 5000 
+
+char* escape(char to[], const char from[]);
+char* etr(char to[], const char from[]);
+
+int 
+main(void)
+{
+  int i;
+  char input;
+  char str[MAXLEN];
+  char e[MAXLEN];
+  char r[MAXLEN];
+
+  for (i = 0; (input = getchar()) != EOF && i+1 < MAXLEN; ++i)
+    str[i] = input;
+
+  str[i] = '\0';
+  
+
+  if (str[i-1] != '\n')
+    printf("\n");
+
+  printf("%s\n", escape(e, str));
+  printf("%s\n", etr(r, e));
+
+  return 0;
+}
+
+char* 
+escape(char to[], const char from[])
+{
+  int i, j;
+
+  for (i = j = 0; from[i] != '\0' && j+1 < MAXLEN; ++i)
+    switch (from[i]) {
+      case '\n' :
+        to[j++] = '\\';
+        to[j++] = 'n';
+        break;
+      case '\t' :
+        to[j++] = '\\';
+        to[j++] = 't';
+        break;
+      case '\a' :
+        to[j++] = '\\';
+        to[j++] = 'a';
+        break;
+      case '\b' :
+        to[j++] = '\\';
+        to[j++] = 'b';
+        break;
+      case '\f' :
+        to[j] = '\\';
+        to[j++] = 'f';
+        break;
+      case '\r' :
+        to[j++] = '\\';
+        to[j++] = 'r';
+        break;
+      case '\v' :
+        to[j++] = '\\';
+        to[j++] = 'v';
+        break;
+      default:
+        to[j++] = from[i];
+        break;
+    }
+
+  to[i] = '\0';
+
+  return to;
+}
+
+char*
+etr(char to[], const char from[])
+{
+  int i, j;
+
+  for (i = j = 0; from[i] != '\0'; ++i) {
+    if (from[i] == '\\')
+      switch (from[++i]) {
+        case 'n' :
+          to[j++] = '\n';
+          break;
+        case 't' :
+          to[j++] = '\t';
+          break;
+        case 'a' :
+          to[j++] = '\a';
+          break;
+        case 'b' :
+          to[j++] = '\b';
+          break;
+        case 'f' :
+          to[j++] = '\f';
+          break;
+        case 'r' :
+          to[j++] = '\r';
+          break;
+        case 'v' :
+          to[j++] = '\r';
+          break;
+        default :
+          to[j++] = '\\';
+          to[j++] = from[i];
+          break;
+      }
+
+    else
+      to[j++] = from[i];
+  }
+
+  to[j] = '\0';
+
+  return to;
+}
diff --git a/3.4.c b/3.4.c
new file mode 100644
index 0000000..51386c6
--- /dev/null
+++ b/3.4.c
@@ -0,0 +1,57 @@
+#include <stdio.h>
+
+#define MAXLEN 15
+
+void reverse(char str[]);
+char* itoa(int n, char str[]);
+
+int 
+main(void)
+{
+  int n = -2147483648;
+  char str[MAXLEN];
+
+  printf("%d\n", n);
+  printf("%s\n", itoa(n, str));
+
+  return 0;
+}
+
+void
+reverse(char str[])
+{
+  int i, j;
+  char temp;
+
+  for (j = 0; str[j] != '\0'; j++)
+    ;
+
+  for (i = 0, --j; i < j; i++, j--) {
+    temp = str[i];
+    str[i] = str[j];
+    str[j] = temp;
+  }
+}
+
+char*
+itoa(int n, char str[])
+{
+  int sign, i;
+
+  if ((sign = n) < 0)
+    n = -n;
+
+  i = 0;
+  do {
+    str[i++] = n%10 + '0';
+  } while ((n /= 10) > 0);
+
+  if (sign <0)
+    str[i++] = '-';
+
+  str[i] = '\0';
+
+  reverse(str);
+
+  return str;
+}