5.6

5 files changed, 383 insertions, 0 deletions

diff --git a/5.6.1.c b/5.6.1.c
new file mode 100644
index 0000000..1810198
--- /dev/null
+++ b/5.6.1.c
@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <ctype.h>
+
+#define MAXLEN 64
+
+int sneed_getline(char str[], int max);
+double atof(const char str[]);
+
+int 
+main(void)
+{
+  char str[MAXLEN];
+
+  while (sneed_getline(str, MAXLEN) > 0)
+    printf("%f\n\n", atof(str));
+
+  return 0;
+}
+
+int
+sneed_getline(char str[], int max)
+{
+  char input;
+  char *str_og = str;
+
+  while (--max && (*str = input = getchar()) != EOF && input != '\n')
+    str++;
+
+  if (!max && input != '\n')
+    *str = '\n', str++;
+
+  str = '\0';
+
+  return str - str_og;
+}
+
+double 
+atof(const char str[])
+{
+  int i, sign, e_sign, j;
+  double val, power, e_power;
+
+  for (i = 0; isspace(str[i]); i++)
+    ;
+  sign = (str[i] == '-') ? -1 : 1;
+
+  if (str[i] == '-' || str[i] == '+')
+    i++;
+
+  for(val = 0.0; isdigit(str[i]); i++)
+    val = val * 10.0 + (str[i] - '0');
+
+  if (str[i] == '.')
+    i++;
+
+  for(power = 1.0; isdigit(str[i]); i++) {
+    val = 10 * val + (str[i] - '0');
+    power *= 10.0;
+  }
+
+  if (str[i] == 'e' || str[i] == 'E')
+    i++;
+
+  e_sign = (str[i] == '-') ? -1 : 1;
+
+  if (str[i] == '-' || str[i] == '+')
+    i++;
+
+  for (e_power = 0.0; isdigit(str[i]); i++)
+    e_power = e_power * 10 + (str[i] - '0');
+
+  if (e_sign < 0)
+    for (j = 0; j < e_power; j++)
+      power *= 10.0;
+  else
+    for (j = 0; j < e_power; j++)
+      power /= 10.0;
+
+  return (sign * val / power);
+}
diff --git a/5.6.2.c b/5.6.2.c
new file mode 100644
index 0000000..d29afc6
--- /dev/null
+++ b/5.6.2.c
@@ -0,0 +1,61 @@
+#include <stdio.h>
+
+#define MAXLEN 15
+
+void reverse(char str[]);
+char* itoa(int n, char str[]);
+
+int 
+main(void)
+{
+  int n = -147483647;
+  char str[MAXLEN];
+
+  printf("%d\n", n);
+  printf("%s\n", itoa(n, str));
+
+  return 0;
+}
+
+void
+reverse(char str[])
+{
+  char temp, *str_og;
+
+  str_og = str;
+
+  while (*str++)
+    ;
+  str -= 2;
+
+  while (str_og < str) {
+    temp = *str_og;
+    *str_og++ = *str;
+    *str-- = temp;
+  }
+}
+
+char*
+itoa(int n, char str[])
+{
+  int sign;
+  char *str_og = str;
+
+  /* to include the most -ve int */
+  n = ((sign = n) < 0) ? -(n+1) : n-1;
+
+  do {
+    *str++ = n%10 + '0';
+  } while ((n /= 10) > 0);
+
+  if (sign <0)
+    *str++ = '-';
+
+  /* part of "to include the most -ve int" */
+  *str_og += 1;
+  *str = '\0';
+
+  reverse(str_og);
+
+  return str_og;
+}
diff --git a/5.6.3.c b/5.6.3.c
new file mode 100644
index 0000000..a186c1f
--- /dev/null
+++ b/5.6.3.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+
+#define MAXLEN 1000
+
+int get_line(char line[], const int max);
+int strindex(char source[], char pattern[]);
+
+int 
+main(void)
+{
+  int found, rightmost;
+  char line[MAXLEN];
+
+  char pattern[] = "ould";
+  found  = 0;
+
+  while (get_line(line, MAXLEN) > 0)
+    if ((rightmost = strindex(line, pattern)) >= 0) {
+      printf("%s >> match at char %d\n", line, rightmost+1);
+      found++;
+    }
+
+  printf("\nSneedGrep found %d match%s\n", found, (found > 0) ? "es" : "");
+
+  return 0;
+}
+
+int 
+get_line(char line[], const int max)
+{
+  int i;
+  char input;
+
+  for (i = 0; (input = getchar()) != EOF && input != '\n' && i < max-2; i++)
+    line[i] = input;
+
+  if (input == '\n' && i < max-2)
+    line[i++] = '\n';
+
+  line[i] = '\0';
+
+  return i;
+}
+
+int 
+strindex(char source[], char pattern[])
+{
+  int i, rightmost;
+  char *source_og = source;
+
+  rightmost = -1;
+
+  for (; *source; source++) {
+    for (i = 0; *(pattern +i) && *(source+i) == *(pattern+i); i++)
+      ;
+
+    if (!*(pattern+i))
+      rightmost = source - source_og;
+  }
+
+  return rightmost;
+}
diff --git a/5.6.4.c b/5.6.4.c
new file mode 100644
index 0000000..bec00f1
--- /dev/null
+++ b/5.6.4.c
@@ -0,0 +1,133 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <math.h>
+
+#define MAXOP 100
+#define NUMBER_SIG '0'
+
+double pop(void);
+void push(double f);
+char getop(char str[]);
+
+int 
+main(void)
+{
+  char str[MAXOP];
+  char type;
+  double op2;
+
+  while ((type = getop(str)) != EOF) {
+    switch (type) {
+      case NUMBER_SIG :
+        push(atof(str));
+        break;
+      case '+' :
+        push(pop() + pop());
+        break;
+      case '*' :
+        push(pop() * pop());
+        break;
+      case '-' :
+        op2 = pop();
+        push(pop() - op2);
+        break;
+      case '/' :
+        if ((op2 = pop()) == 0.0)
+          printf("Err: deviser cant be zero\n");
+        else 
+          push(pop() / op2);
+
+        break;
+      case '%' :
+        op2 = pop();
+        if (op2 != 0)
+          push(fmod(pop(), op2));
+        else 
+          printf("Err: deviser cant be zero\n");
+
+        break;
+      case '\n' :
+        printf("%.8g\n", pop());
+        break;
+      default :
+        printf("Err: unknown command\n");
+    }
+  }
+
+  return 0;
+}
+
+#define MAXVAL 100
+double val[MAXVAL];
+int sp = 0;
+
+double 
+pop(void)
+{
+  if (sp > 0)
+    return val[--sp];
+  else {
+    printf("Err: stack empty\n");
+    return 0.0;
+  }
+}
+
+void
+push(double f)
+{
+  if (sp < MAXVAL)
+    val[sp++] = f;
+  else
+    printf("Err: stack is full\n");
+}
+
+char getch(void);
+void ungetch(char input);
+
+char 
+getop(char str[])
+{
+  char input, *str_og;
+
+  str_og = str;
+
+  /* ignore blanks */
+  while (isblank(input = *str = getch()));
+  
+  /* return operator */
+  if (!isdigit(input) && input != '.')
+    return input;
+
+  /* collect digits*/
+  while (str - str_og < MAXOP && (isdigit(input=getch()) || input == '.'))
+    *++str = input;
+
+  *++str = '\0';
+
+  if (input != EOF)
+    ungetch(input);
+
+  return NUMBER_SIG;
+}
+
+#define MAXBUFF 100
+char buff[MAXBUFF];
+int bp = 0;
+
+char
+getch(void)
+{
+  return (bp > 0) ? buff[--bp] : getchar();
+}
+
+void
+ungetch(char input)
+{
+  if (bp < MAXBUFF)
+    buff[bp++] = input;
+  else {
+    printf("Err: buffer full\n");
+  }
+}
+
diff --git a/5.6.5.c b/5.6.5.c
new file mode 100644
index 0000000..d04da1e
--- /dev/null
+++ b/5.6.5.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <ctype.h>
+
+#define MAXLEN 1000
+
+int atoi(char str[]);
+int sneed_getline(char str[], int max);
+
+int 
+main(void)
+{
+  char str[MAXLEN];
+  while (sneed_getline(str, MAXLEN)) {
+    printf("string ver : %s", str);
+    printf("int    ver : %d\n", atoi(str));
+  }
+  return 0;
+}
+
+int 
+atoi(char str[])
+{
+  int val;
+
+  for (val = 0; isdigit(*str) && *str; str++)
+    val = val * 10 + *str -'0';
+
+  return val;
+}
+
+int
+sneed_getline(char str[], int max)
+{
+  char input;
+  char *str_og = str;
+
+  while (--max && (*str = input = getchar()) != EOF && input != '\n')
+    str++;
+
+  if (!max && input != '\n')
+    *str = '\n', str++;
+
+  str = '\0';
+
+  return str - str_og -1;
+}
+