C&Cpp未初始化全局变量与局部变量结果

C&Cpp未初始化全局变量与局部变量结果

gcc 版本

GCC version: 11.2.0

以下代码输出GCC版本信息

#include <iostream>

using namespace std;

int main()
{

    cout << "GCC version: " << __GNUC__ << "." << __GNUC_MINOR__ << "." << __GNUC_PATCHLEVEL__ << endl;
    return 0;
}

在命令行中输入gcc --version显示更详细的版本信息

gcc.exe (x86_64-posix-seh-rev3, Built by MinGW-W64 project) 11.2.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE

Cpp演示

#include <iostream>

using namespace std;

int a;

int main()
{
    int b;

    /* 全局变量与局部变量如果不加指定 将会自动初始化为零 */
    /* 但不建议这样使用 */
    cout << "a = " << a << endl;
    cout << "b = " << b << endl;
    return 0;
}

输出结果展示

a = 0
b = 0

C语言演示

#include <stdio.h>

int a;

int main()
{
    int b;
    printf("a = %d\n", a);
    printf("b = %d", b);

    return 0;
}

输出结果展示

a = 0
b = 0