修复下面代码#include<iostream> using namespace std; void Show() { printf("请输入想选择的指令:\n"); printf("1.显示串\n"); printf("2.显示串长\n"); printf("3.两串做比较\n"); printf("4.求子串\n"); printf("5.定位\n"); printf("0.退出\n"); printf("-------------------\n"); } int main() { int n; Show(); scanf("%d", &n); char s[15] = "qwertasdfzxc"; HString S; StrAssign(S, s); char t[5] = "asdf"; HString T; StrAssign(T, t); HString Sub; while (n != 0) { switch (n) { case 1: printf("第一个串为：%s\n", S.ch); printf("第二个串为：%s\n", T.ch); break; case 2: printf("第一条串长：%d\n", StrLength(S)); printf("第二条串长：%d\n", StrLength(T)); break; case 3: int n; n = StrCompare(S, T); if (n != 0) if (n > 0) printf("前面长\n"); else printf("后面长\n"); else printf("一样长\n"); break; case 4:printf("请输入你想取的位置及长度:\t"); int j, l; scanf("%d %d", &j, &l); SubString(Sub, S, j, l); StrPrint(Sub); break; case 5: int k; printf("输入查询的位置:\n"); scanf("%d", &k); int x = Index(S, T, k); printf("定位到的位置为：%d", x); break; } printf("\n"); Show(); scanf("%d", &n); } return 0; }

修复后的代码如下：

#include<iostream> 
using namespace std; 

void Show() { 
    cout << "请输入想选择的指令:" << endl; 
    cout << "1.显示串" << endl; 
    cout << "2.显示串长" << endl; 
    cout << "3.两串做比较" << endl; 
    cout << "4.求子串" << endl; 
    cout << "5.定位" << endl; 
    cout << "0.退出" << endl; 
    cout << "-------------------" << endl; 
} 

int main() { 
    int n; 
    Show(); 
    cin >> n; 
    char s[15] = "qwertasdfzxc"; 
    HString S; 
    StrAssign(S, s); 
    char t[5] = "asdf"; 
    HString T; 
    StrAssign(T, t); 
    HString Sub; 
    while (n != 0) { 
        switch (n) { 
            case 1: 
                cout << "第一个串为：" << S.ch << endl; 
                cout << "第二个串为：" << T.ch << endl; 
                break; 
            case 2: 
                cout << "第一条串长：" << StrLength(S) << endl; 
                cout << "第二条串长：" << StrLength(T) << endl; 
                break; 
            case 3: 
                int res; 
                res = StrCompare(S, T); 
                if (res != 0) { 
                    if (res > 0) { 
                        cout << "前面长" << endl; 
                    } else { 
                        cout << "后面长" << endl; 
                    } 
                } else { 
                    cout << "一样长" << endl; 
                } 
                break; 
            case 4: 
                cout << "请输入你想取的位置及长度:" << endl; 
                int j, l; 
                cin >> j >> l; 
                SubString(Sub, S, j, l); 
                StrPrint(Sub); 
                break; 
            case 5: 
                int k; 
                cout << "输入查询的位置:" << endl; 
                cin >> k; 
                int x = Index(S, T, k); 
                cout << "定位到的位置为：" << x << endl; 
                break; 
            default: 
                cout << "错误的指令" << endl; 
                break; 
        } 
        Show(); 
        cin >> n; 
    } 
    return 0; 
}

主要的改动如下：

1. 将 printf 改为 cout，将 scanf 改为 cin；

2. case 3 中定义的变量 n 与 main 函数中定义的变量 n 冲突，改为 res；

3. 增加了 default 分支，用于处理错误的指令。