Thread: Help with Replacing Strings/substrings in C

Hi this is my first post on this site. I am a beginner in c in college. I am writing the program in XCode.

My assignment is to ask the user for a string, ask for a substring to replace, ask what to replace it with, and then print out the original string with the replaced substring. I am allowed to use any functions in <string.h> aside from strstr.

i have had errors with my code for a while now and now am receiving the error

Program received signal: “EXC_BAD_ACCESS”.

at the "else" part of the "stringAtStart" function"

for some reason it is not looping properly i think. and when i try debugging it manually "with printf's" that specific "else" keeps running continuously.

i really need your help.

thank you in advance!

Code:

#include <stdio.h>
#include <string.h>

#define Max 40

int stringAtStart(char string1[], char string2[], int Si);

/******
 function name: main
 the input: none
 the output: none
 the function operation: asking the user to pick a number between 1 and 3 and then based on the number picked computing 3 different options 
 ******/
int main (void) 
{
	int pickednum, i;
	char string1[Max], string2 [Max], string3 [Max];
									
	
	do{
		
		do 
		{
			printf("Please enter option\n");
			scanf("%d", &pickednum);
			if (pickednum>3)
				printf("illegal option \n");
			
		} while (pickednum > 3);
		
		
		switch (pickednum) 
		{
			case 1: 
				printf("Please enter a string\n");
				scanf("%s", string1);
				printf("Please enter string to replace\n");
				scanf("%s", string2);
				printf("Please enter replacing string\n");
				scanf("%s", string3);
				//for (i=0; string1 [i] != '\0'; i++)
				
				//printf("%d", contains (string1, string2, i));
				
				for(i=0; i<strlen(string1); i++)
				{
					if(stringAtStart(string1,string2, i))
					{
						puts(string3);
						i=i+strlen(string2);
						printf("4  \n");
					}
					else
						
					   puts (string1[i]);
				}
			

		}	
		
	} while (pickednum !=3);
	
	
	if (pickednum = 3)
		exit;
}

int stringAtStart(char string1[], char string2[], int Si)
{
	
	int i = Si, index=0, counter = strlen(string1), inString = 0;
	
	for (i ; index < strlen(string2); i++)
	{
		if (counter == 0)
		{
			inString =1;
			printf("1 %d\n", counter);
			break;
		}
		if ((string1[i] == string2[index]) )
		{
			counter --;
			index ++;
			printf("2 counter = %d    lengthofstring2 = %d   string2= %d index = %d\n", counter,strlen(string2), strlen(string1),index);
		}
		else
		{
			counter = strlen(string1);
			index=0;
			printf("3  counter = %d  index = %d\n", counter, index);
		}
	}
		return inString;

}