Thread: Check string for characters and concat characters to new string?

Recursion does not appear to be used in your code snippet. Furthermore, it is badly in need of proper indentation, e.g.,

Code:

for (i = 0; s1[i] != '\0'; i++)
{
    if (s1[i] == 'x'|| s1[i] == 'y'|| s1[i] == 'z')
    {
        printf("\n%c", s1[i]);
    }
}

Anyway, if you did use recursion, one approach would be to pass a pointer to (the first character of) the destination string as an argument. This way, the call that should do the copying writes to the destination string using this pointer.

I suggest that you post the smallest and simplest program that you expect to compile, but which demonstrates the error.

Based on the error message, my guess is that s2 is a char, so you should just assign to that char, but because I cannot see the declaration of s2, I cannot be certain.

Thanks for the reply. Here is a small version of what I'm trying to accomplish:

Code:

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


int main(void)
{
    char s1[50], s2[50], *ptr;
    int i;
    
    printf (" Enter String : \n");
    scanf (" %s ", s1);
    
    printf (" New string : \n");
    
    ptr = s1;


    for (i = 0; s1[i] != '\0'; i++)
    {
        if (s1[i] == 'x' || s1[i] == 'y' || s1[i] == 'z')
        {
            ptr = &s1[i];
            strcat(s2, *ptr);
        }
    printf (" %s \n", *ptr); //Just to be clear, lets say the user entered the string "abcxyz", the output would be "xyz".
    }
}

It gives me the error: (using dev-cpp if that means anything)
[Error] invalid conversion from 'char' to 'const char*' [-fpermissive]
[Note] initializing argument 2 of 'char* strcat(char*, const char*)'

To append a single char using strcat, you have to make a small string out of it.

Code:

char temp[2] = { 0 };
temp[0] = s1[i];
strcat(s2, temp);

Your code also needs to ensure that s2 is an empty string before calling strcat for the first time.