#include <stdio.h>
#include <string.h>
 
int insertCharToString(int index,char str[],char ch);
int main(void) {
	char str[10] = "abcde";
 
	insertCharToString(3,str,'w');
	printf("%s\n",str);
}
 
int insertCharToString(int index,char str[],char ch)
{
	int length = strlen(str);
	int i = 0;
	if(index > length || index < 0) {
		printf("Invalid insert index!\n");
		return -1;
	}
 
	for(i = length - 1; i >= index; i--) {
		str[i + 1] = str[i]; 
	}
	str[length + 1] = '\0';
	str[index] = ch;
 
	return 1;
}

I2luY2x1ZGUgPHN0ZGlvLmg+CiNpbmNsdWRlIDxzdHJpbmcuaD4KCmludCBpbnNlcnRDaGFyVG9TdHJpbmcoaW50IGluZGV4LGNoYXIgc3RyW10sY2hhciBjaCk7CmludCBtYWluKHZvaWQpIHsKCWNoYXIgc3RyWzEwXSA9ICJhYmNkZSI7CgkKCWluc2VydENoYXJUb1N0cmluZygzLHN0ciwndycpOwoJcHJpbnRmKCIlc1xuIixzdHIpOwp9CgppbnQgaW5zZXJ0Q2hhclRvU3RyaW5nKGludCBpbmRleCxjaGFyIHN0cltdLGNoYXIgY2gpCnsKCWludCBsZW5ndGggPSBzdHJsZW4oc3RyKTsKCWludCBpID0gMDsKCWlmKGluZGV4ID4gbGVuZ3RoIHx8IGluZGV4IDwgMCkgewoJCXByaW50ZigiSW52YWxpZCBpbnNlcnQgaW5kZXghXG4iKTsKCQlyZXR1cm4gLTE7Cgl9CgkKCWZvcihpID0gbGVuZ3RoIC0gMTsgaSA+PSBpbmRleDsgaS0tKSB7CgkJc3RyW2kgKyAxXSA9IHN0cltpXTsgCgl9CglzdHJbbGVuZ3RoICsgMV0gPSAnXDAnOwoJc3RyW2luZGV4XSA9IGNoOwoJCglyZXR1cm4gMTsKfQ==