Dem_Chuoi.cpp

// Dem_Chuoi.cpp
#include <iostream>
#include <string.h>

using namespace std;

void xoaKyTu(char str[255], int k) {
	for (int i = k; i < strlen(str); i++)
		str[i] = str[i+1];
}

void chenKyTu(char str[255], char x, int k) {
	int n = strlen(str);
	for (int i = n; i > k ; i--)
		str[i] = str[i-1];
	str[k] = x;
	str[n+1] = '\0';
}

int demChuoi(char inputStr[100], char findStr[100]) {
	int n = 0;
	bool find_ok = false;
	for (int i = 0; i < strlen(inputStr); i++) {
		for (int j = 0; j < strlen(findStr); j++) {
			if (inputStr[i+j] != findStr[j]) {
				find_ok = false;
				break;
			}
			find_ok = true;
		}
		if (find_ok) {
			n++;
		}
	}
	return n;
}

void thayTheChuoi(char inputStr[100], char findStr[100], char replaceStr[100]) {
	bool find_ok = false;
	for (int i = 0; i < strlen(inputStr); i++) {
		for (int j = 0; j < strlen(findStr); j++) {
			if (inputStr[i+j] != findStr[j]) {
				find_ok = false;
				break;
			}
			find_ok = true;
		}
		if (find_ok) {
			for (int k = 0; k < strlen(findStr); k++) {
				xoaKyTu(inputStr, i);
			}
			for (int k = 0; k < strlen(replaceStr); k++) {
				chenKyTu(inputStr, replaceStr[k], i + k);
			}
		}
	}
}

int main() {
	char str1[100], str2[100], str3[100];
	cout<<"Nhap str1: "; fflush(stdin); gets(str1);
	cout<<"Nhap str2: "; fflush(stdin); gets(str2);
	cout<<"Nhap str3: "; fflush(stdin); gets(str3);
	cout<<"So lan xuat hien: "<<demChuoi(str1, str2)<<endl;
	thayTheChuoi(str1, str2, str3);
	cout<<"Chuoi sau khi thay the: "<<str1<<endl;
	return 0;
}