c++ - 在 C++ 中调整数组大小时如何修复错误？

Question

我有一个返回一行输入字符的小程序:

#include <iostream>

char *resize(const char *str, unsigned size, unsigned new_size);  

char *resize(const char *str, unsigned size, unsigned new_size)
{
    char * m = new char[new_size];
    for (int i = 0; i < size && i < new_size; ++i) {
        m[i] = str[i];
    }
    delete [] str;
    return m;
}


char *getline()
{
    char ch;
    std::cin >> ch;

    int size = 1;
    char * str = new char[size];
    char * m;

    while (std::cin.get(ch) && ch != '\n') {

        str[size-1] = ch;
        m = resize(str, size, ++size);
        m[size] = '\0';

    }
    return m;
}

但它给了我一个错误:

Failed test #1. Runtime error terminate called after throwing an instance of 'std::logic_error' what(): Memory leak or double allocation occured Aborted (core dumped)

我不完全明白问题出在哪里，因为我是 C++ 的新手。如何解决问题？

Answer 1

这里有一个问题:m = resize(str, size,++size);。函数参数的计算顺序未指定，因此允许编译器在将 size 的值作为第二个参数传递之前递增 size。将代码重写为 m = resize(str, size, size+1);++大小；。