C | String | Question 1 - GeeksforGeeks

Consider the following code. The function myStrcat concatenates two strings. It appends all characters of b to end of a. So the expected output is “Geeks Quiz”. The program compiles fine but produces segmentation fault when run.

#include <stdio.h> 
  
void myStrcat(char *a, char *b) 
{ 
    int m = strlen(a); 
    int n = strlen(b); 
    int i; 
    for (i = 0; i <= n; i++) 
       a[m+i]  = b[i]; 
} 
  
int main() 
{ 
    char *str1 = "Geeks "; 
    char *str2 = "Quiz"; 
    myStrcat(str1, str2); 
    printf("%s ", str1); 
    return 0; 
} 

Which of the following changes can correct the program so that it prints “Geeks Quiz”?
(A) char *str1 = “Geeks “; can be changed to char str1[100] = “Geeks “;
(B) char *str1 = “Geeks “; can be changed to char str1[100] = “Geeks “; and a line a[m+n-1] = ‘\0’ is added at the end of myStrcat
(C) A line a[m+n-1] = ‘\0’ is added at the end of myStrcat
(D) A line ‘a = (char *)malloc(sizeof(char)*(strlen(a) + strlen(b) + 1)) is added at the beginning of myStrcat()

Answer: (A)

Explanation: See following for explanation.

https://www.geeksforgeeks.org/storage-for-strings-in-c/

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