Write a program that replaces all occurrences of a string STR1 with the string STR2 in a string STR. Use a END to save the string during the replacement.

Examples:

• replacing all occurrences of 'PHON' by 'OY' in 'ALPHONSE' gives 'ALOYSE'
• replacing all occurrences of 'AN' by 'ONT' in 'BANANE' gives 'BONTONTE'
• replacing all occurrences of 'T' by 'Y' in 'TOTALEMENT' gives 'YOYALEMENY'
• replacing all occurrences of '' by 'TTT' in 'HELLO' gives 'HELLO'
• replacing all occurrences of 'L' by '' in 'HELLO' gives 'HEO'

#include <stdio.h>
#include <conio.h>

void main()
{
	/* Declarations */
	char STR[100]; /* string to transform */
	char STR1[100]; /* string to find  */
	char STR2[100]; /* replacement string */
	char END[100]; /* string to display */
	int I;      /* counter for STR */
	int J;      /* counter for STR1 and STR2 */
	int K;      /* counter for copy  */


	/* Read */
	printf("Enter the string to find STR1      : ");
	gets(STR1);
	printf("Enter the replacement string STR2  : ");
	gets(STR2);
	printf("Enter the  string to transform STR : ");
	gets(STR);

	/* find STR1 in STR */
	for (I = 0; STR[I]; I++)
		if (STR[I] == STR1[0])
		{
			for (J = 1; STR1[J] && (STR1[J] == STR[I + J]); J++)
				;
			if (STR1[J] == '\0') /* FOUND ! */
			{
				/* Now I indicates the position of STR1 */
				/* in STR and J indicates the length of STR1 */
				/* Save the end of STR in END */
				for (K = 0; STR[K + I + J]; K++)
					END[K] = STR[K + I + J];
				END[K] = '\0';
				/* Copy STR2 to STR and move  */
				/* I behind the copy of STR2. */
				for (K = 0; STR2[K]; K++, I++)
					STR[I] = STR2[K];
				/* Recopy END to STR */
				for (K = 0; END[K]; K++)
					STR[I + K] = END[K];
				/* Terminate the STR string */
				STR[I + K] = '\0';
				I--; /* readjust the I counter */
			}
		}

	/* display */
	printf("Resulting string : \"%s\"\n", STR);
	getch();
}