How to replace a substring in a string in the C language?

1 year ago
Liam
1 minute

In C language, you can use library functions strstr() and strcpy() to replace a substring within a string. The specific steps are as follows:

  1. The function strstr()
  2. Copy the preceding part of the substring to a new string.
  3. Copy the new substring to a new string for replacement.
  4. Copy the remaining portion of the substring to a new string.
  5. The function strcpy() is used to copy a string to another string.

Here is a sample code for replacing a substring in a string:

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

void replaceSubstring(char *original, char *substring, char *replacement) {
    char newString[1000];
    char *ptr;
    strcpy(newString, original);
    
    while ((ptr = strstr(newString, substring))) {
        strcpy(ptr, replacement);
        strcpy(ptr + strlen(replacement), ptr + strlen(substring));
    }
    
    strcpy(original, newString);
}

int main() {
    char str[1000] = "hello world";
    
    printf("Original string: %s\n", str);
    
    replaceSubstring(str, "world", "everyone");
    
    printf("Updated string: %s\n", str);
    
    return 0;
}

In this example, we have defined a replaceSubstring() function to replace a substring in a string. In the main() function, we first output the original string, then call the replaceSubstring() function to replace “world” with “everyone”, and finally output the updated string.

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