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我正在尝试从用户输入中读取字符串，然后将其打印在屏幕上。但是，当在控制台上打印字符串时，它有点乱码。有趣的是它在 Visual Studio 中工作，而不是在 CodeBlocks 中。

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

int main() {
    int i, num_bytes;
    char sentence[] = "";
    std::cout << "Please enter your name: ";
    //fgets(sentence, 100, stdin);
    //scanf("%[^\n]%*c", sentence);
    //scanf("%[^\n]", sentence);
    std::cin >> sentence;
    num_bytes = strlen(sentence);

    LPVOID ptr = VirtualAlloc(NULL, num_bytes, MEM_RESERVE, PAGE_READWRITE);
    ptr = VirtualAlloc(ptr, num_bytes, MEM_COMMIT, PAGE_READWRITE);

    if (ptr) {
        char* char_ptr = static_cast<char*>(ptr);

        for (i = 0; i < num_bytes; i++) {
            char_ptr[i] = sentence[i];
        }

        std::cout << "Allocated Memory Address: " << (void *)ptr << std::endl;

        std::cout << "Press Enter to print out the characters.\n";
        getchar();

        for (i = 0; i < num_bytes; i++) {
            std::cout << char_ptr[i];
        }

        std::cout << "\nPress Enter to clear memory." << std::endl;
        getchar();

        VirtualFree(ptr, 0, MEM_RELEASE);
    } else {
        std::cout << "Could not allocate " << num_bytes << " of memory." << std::endl;
    }

    std::cout << "\nPress Enter to continue." << std::endl;
    getchar();
}
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2 回答 2

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您应该明确指定字符串的内存大小。该代码：

char sentence[] = "";

声明最大大小为 0 的句子（+1 零符号）。当然，您将更多数据写入非您的内存中。试试这个：

char sentence[200] = "";
于 2021-12-22T14:08:24.070 回答
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而不是这个：

    char sentence[] = "";
    std::cout << "Please enter your name: ";
    //fgets(sentence, 100, stdin);
    //scanf("%[^\n]%*c", sentence);
    //scanf("%[^\n]", sentence);
    std::cin >> sentence;
    num_bytes = strlen(sentence);

你最好写这个：

    constexpr std::streamsize BUFFER_SIZE { 100 };
    std::array<char, BUFFER_SIZE> sentence { }; // use the more modern std::array

    std::cout << "Please enter your name: ";
    std::cin.getline( sentence.data( ), BUFFER_SIZE ); // will only read 100 chars
                                                       // including spaces and tabs

    num_bytes = strlen(sentence.data( ));

其余的与您的代码相同。但是现在用户也可以输入空格字符并且它们不会导致缓冲区溢出，因为std::cin.getline只会从标准输入流中读取有限数量的字符。

于 2021-12-22T15:50:48.800 回答