String: Sustituir asterisco

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

int main(){
	char cadena[50], subcadena[50], sustituir = '*';
	int i = 0, j = 0, largocadena, largosubcadena;
	
	printf("Escribe una frase: \n");
	gets(cadena);
	printf("Escribe la coincidencia que buscas: \n");
	gets(subcadena);
	
	largocadena = strlen(cadena);
	largosubcadena = strlen(subcadena);
	
	for(i=0; i<largocadena; i++){
		if(cadena[i] == subcadena[0]){
			for(j=1; j<largosubcadena; j++){
				if(cadena[i+j] == subcadena[j]){
					if(j == largosubcadena-1) cadena[i] = sustituir;
				}
			}
		}
	}
	printf("\n%s \n%s \n",subcadena, cadena);
	
	system("pause");
	return 0;
}