2 files changed, 141 insertions, 0 deletions
diff --git a/4.1.c b/4.1.c
new file mode 100644
index 0000000..e848d0c
--- /dev/null
+++ b/4.1.c
@@ -0,0 +1,61 @@
+#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, j, k, rightmost;
+
+  rightmost = -1;
+
+  for (i = 0; source[i] != '\0'; i++) {
+    for (j = i, k = 0; pattern[k] != '\0' && source[j] == pattern[k]; j++, k++)
+      ;
+
+    if (pattern[k] == '\0')
+      rightmost = i;
+  }
+
+  return rightmost;
+}
diff --git a/4.2.c b/4.2.c
new file mode 100644
index 0000000..5739824
--- /dev/null
+++ b/4.2.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)
+{
+  int i;
+  char input;
+
+  for (i = 0; i < max && (input = getchar()) != EOF && input != '\n'; i++)
+    str[i] = input;
+
+  if (i < max && input != '\n')
+    str[i++] = '\n';
+
+  str[i] = '\0';
+
+  return i;
+}
+
+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;
+  else
+    for (j = 0; j < e_power; j++)
+      power /= 10;
+
+  return (sign * val / power);
+}