c++ - 将 char* 转换为 int

Question

我目前正在尝试将整数转换为 char* 以便通过套接字发送它。在接收方法中，我逻辑上尝试再次将 char* 视为整数，但我似乎遗漏了一些东西，因为我无法正确处理。

#include <iostream>

using namespace std;

int main(int argc, char** argv) {

    int num1 = 42;          // Works
    int num2 = 100;         // Works
    int num3 = 126;         // Works
    int num4 = 517;         // Doesn't seem to work for int > 127

    char p1[sizeof(int)];
    *p1 = num1;
    char p2[sizeof(int)];
    *p2 = num2;
    char p3[sizeof(int)];
    *p3 = num3;
    char p4[sizeof(int)];
    *p4 = num4;

    void* pA = p4;
    void* pB = &num4;

    int result1 = static_cast<int>(*p1);
    int result2 = static_cast<int>(*p2);
    int result3 = static_cast<int>(*p3);
    int result4 = static_cast<int>(*p4);

    int resultV1 = *static_cast<int*>(pA);
    int resultV2 = *reinterpret_cast<int*>(p3);
    unsigned int resultV3 = static_cast<int>(*p4);
    int resultV4 = *static_cast<int*>(pB);              // Works, but I need to convert a char* into an int, not a void* into an int

    cout << "R1:        " << result1 << endl;
    cout << "Expected:  " << num1 << endl << endl;
    cout << "R2:        " << result2 << endl;
    cout << "Expected:  " << num2 << endl << endl;
    cout << "R3:        " << result3 << endl;
    cout << "Expected:  " << num3 << endl << endl;
    cout << "R4:        " << result4 << endl;
    cout << "Expected:  " << num4 << endl << endl;
    cout << "RV1:       " << resultV1 << endl;
    cout << "Expected:  " << num4 << endl << endl;
    cout << "RV2:       " << resultV2 << endl;
    cout << "Expected:  " << num4 << endl << endl;
    cout << "RV3:       " << resultV3 << endl;
    cout << "Expected:  " << num4 << endl << endl;
    cout << "RV4:       " << resultV4 << endl;
    cout << "Expected:  " << num4 << endl << endl;

    getchar();
    return 0;
}

我现在完全不知道如何解决这个问题。我尝试了其他几种方法，但它们似乎都无法正常工作。必须首先将整数转换为 char*，因为 WinSock-API 中的 recv() 方法将其读取的字节存储在缓冲区字符数组中。

任何解释或解决方案？提前致谢。

Answer 1

如果你不想使用 C 风格的指针，也许你可以试试这个。

void int2CharArr(int num, char* p1){
    p1[0] = num & 0xFF;
    p1[1] = (num >> 8) & 0xFF;
    p1[2] = (num >> 16) & 0xFF;
    p1[3] = (num >> 24) & 0xFF;
}

int charArr2Int(char* p1){
    return (p1[3] << 24) + (p1[2] << 16) + (p1[1] << 8) + p1[0];
}

void test(){
    int a = 0x12345678;
    char q[sizeof(int)];
    int2CharArr(a, q);
    int b = charArr2Int(q);
    printf("%x , %x , %x , %x\n", *q, *(q+1), *(q+2), *(q+3));
    printf("%x\n", b);
}