ex11-2_insert.c

#include <stdio.h>

int strLen(char *s) {
  char *sPointer = s;
  while (*sPointer) {
    sPointer++;
  }
  return sPointer - s;
}

int strCpy(int i, char *a, char *b) {
  a += i - 1;
  for (; *b != '\0'; a++, b++) {
    *a = *b;
  }
  *a = '\0';
  return 0;
}

int strIns(int i, char *buf, char *text) {
  int n;
  char tmpStr[255];
  char *tmp = tmpStr;
  buf += i;
  while (*buf != '\0') {
    strCpy(strLen(buf), buf, tmp);
  }
  buf -= i;
  strCpy(i, buf, text);
  //strCpy(strLen(buf), buf, tmp);
  return 0;
}

int main() {
  int i;
  char a[255], b[255];
  printf("Copy position > ");
  scanf("%d", &i);
  printf("a > ");
  scanf("%20s", a);
  printf("b > ");
  scanf("%20s", b);
  // strCpy(i, a, b);
  strIns(i, a, b);
  printf("%s\n", a);
}