replaceString.c

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


    int * findIndexOfString(char stringofData[], char stringToFind[]) {
        static int indexOfString[2];
        int i, j;
        int loopCounter = strlen(stringofData) - strlen(stringToFind);
        for (i = 0; i < strlen(stringofData); i++) {
            for (j = 0; j < strlen(stringToFind); j++) {
                if ((char) stringofData[i] == (char) stringToFind[j]) {
                    if (j == 0) {
                        indexOfString[0] = i;
                    } else if (j == ((int)strlen(stringToFind) - 1)) {
                        indexOfString[1] = indexOfString[0] + j;
                    }
                    continue;
                }
            }
        }
        return indexOfString;
    }

    void splitString(char string[] , int start , int end){
        char returnString[100];
        int i;
        for(i = start; i < end ; i++){
            returnString[i] = string[i];
            printf("%c" , string[i]);
        }
    }
    void replaceString(char oldString[] , char newString[] , int *a){
        int i ; 
        if(a[1] != 0){
            splitString(oldString , 0 , a[0]);
            for(i = 0 ; i < strlen(newString) ; i++){
                printf("%c" , newString[i]);
            }
            splitString(oldString , a[1] + 1 , strlen(oldString));
        }
    }
int main() {
    int i;
    char fullString[100];
    char patternToFind[100];
    char stringToReplace[100];
    printf("Enter a string: ");
    scanf("%[^\n]%*c" ,fullString);
    printf("Enter old string: ");
    scanf("%[^\n]%*c" ,patternToFind);
    printf("Enter  new string: ");
    scanf("%[^\n]%*c" ,stringToReplace);
    int *indexOfPatternString;
    indexOfPatternString = findIndexOfString(fullString, patternToFind);
    replaceString(fullString , stringToReplace , indexOfPatternString);
    return 0 ;
}