字符修改（题目）

#include<bits/stdc++.h>
using namespace std;
int main() {
	char a, b;
	char n[255], m[255];
	int x = 0;
	for (int i = 0; i < 255; i++) {
		scanf("%c", &n[x]);
		if (n[x] == '\n') {
			break;
		}
		m[x] = n[x];
		x++;
	}
	cin >> a >> b;
	for (int i = 0; i <= x; i++) {
		if (m[i] == a) {
			m[i] = b;
		}
		cout << m[i];
	}
	return 0;
}