// Program to find one string in another, delete the found string, and replace it with another

#include <stdio.h>
#include <stdbool.h>

int main (void)
{
    char source[81], s1[81], s2[81];
    void readLine (char buffer[]);
    void replaceString (char source[], char s1[], char s2[]);
    void printString (char source[]);

    // Enter source
    printf ("Enter the source string:n");
    readLine (source);

    // Enter string to be replaced
    printf ("Enter the string to be replaced:n");
    readLine (s1);

    // Enter string that will replace
    printf ("Enter the string that will replace the previous one:n");
    readLine (s2);

    // Replace the strings
    replaceString (source, s1, s2);

    // Print the string
    printString (source);

    return 0;
}

void readLine (char buffer[])
{
    char character;
    int i = 0;

    do
    {
        character = getchar ();
        buffer[i] = character;
        i++;
    }
    while ( character != 'n' );

    buffer[i - 1] = '';
}

bool equalCharacter (char a, char b)
{
    if ( a == b )
        return true;

    else
        return false;

}

void replaceString (char source[], char s1[], char s2[])
{
    int start, numberRemove;
    int findString (char string[], char find[]);
    int stringLength (char string[]);
    void removeString (char source[], int start, int numberRemove);
    void inString (char source[], char insertString[], int position);


    start = findString (source, s1);
    numberRemove = stringLength (s1);
    removeString (source, start, numberRemove);

    inString (source, s2, start);

}


 int findString (char string[], char find[])
{
     int i = 0, j = 0, start;

    bool equalCharacter (char a, char b);

    for ( i = 0; string[i] != '' && find[j] != ''; i++ ) {

        if ( equalCharacter (string[i], find[j]) )
            j++;

        else
            j = 0;
}

    if ( j == 0 )
        start = -1;

    else
        start = i - j;


    return start;

}

int stringLength (char string[])
{
    int i, length = 0;

    for (i = 0; string[i] != ''; i++) {
        length++;
    }

    return length;
}

void removeString (char source[], int start, int numberRemove)
{
    int i, j;

    for ( i = start, j = start + numberRemove; i <= start + numberRemove - 1; j++, i++ ){
        source[i] = source[j];
    }


    source[i] = '';


}

void inString (char source[], char insertString[], int position)
{
    int i, j;
    char buffer[81];

    for ( i = position, j = 0; source[i] != ''; i++, j++ ) {
    buffer[j] = source[i];
    }

    buffer[j] = '';


    for ( i = position, j = 0; insertString[j] != ''; i++, j++ ) {
        source[i] = insertString[j];
    }


    for ( j = 0; buffer[j] != ''; i++, j++ ) {
        source[i] = buffer[j];




    source[i] = '';

}

void printString (char source[])
{
    printf ("%s", source);
    printf ("n");
}