string_to_number

#include <stdio.h>
int toString(char []);
int main()
{
  char s[100];
  int n;
  printf("Input a valid string to convert to integer\n");
  scanf("%s", s);
  n = toString(s);
  printf("String  = %s\nInteger = %d\n", s, n);
  return 0;
}

int toString(char s[])
{
  int c, sign, offset, n;
  if (s[0] == '-')
{
    sign = -1;
  }

  if (sign == -1)
    {
    offset = 1;
  }
  else {
    offset = 0;
  }
  n = 0;
  for (c = offset; s[c] != '\0'; c++) {
    n = n * 10 + s[c] - '0';
  }
  if (sign == -1) {
    n = -n;
  }
  return n;
}