lemene

说明

使用char[]和char*定义变量，并赋值字符串常量，这两者有较大区别。前者定义数组，并将字符串常量拷贝至该数组，变量表示这个新数组的首地址。后者定义指针，指向一个字符常量。前者会产生新的字符串数据，并且拥有读写权限，后者不一定产生新字符串数据，并且只有读权限。

实验代码

/**
 * @file char_array_pointer.cpp
 * @brief 测试字符数组和指针
 * @copyrigh public domain
 */
#include <iostream>
const char* string0() {
const char* str = "string";
return str;
}
const char* string1() {
return "string";
}
const char* string2() {
static const char str[] = "string";
return str;
}
const char* string3() {
    char str[] = "string";
    return str;
}
void function() {
    char a[] = "abc123456";
}
void test_string1() {
    const char* str = string1();
    std::cout << "test_string1: " << str << std::endl;
    function();
    std::cout << "test_string1: " << str << std::endl;
}
void test_string2() {
    const char* str = string2();
    std::cout << "test_string2: " << str << std::endl;
    function();
    std::cout << "test_string2: " << str << std::endl;
}
void test_string3() {
    const char* str = string3();
    std::cout << "test_string3: " << str << std::endl;
    function();
    std::cout << "test_string3: " << str << std::endl;
}
int main() {
std::cout << "string0 == string1 is " << (string0() == string1() ? "true" : "false") << std::endl;
std::cout << "string1 == string2 is " << (string1() == string2() ? "true" : "false") << std::endl;
    test_string1();
    test_string2();
    test_string3();
    return 0;
}

运行及结果

$ g++ char_array_pointer.cpp
char_array_pointer.cpp: In function 'const char* string3()':
char_array_pointer.cpp:24:10: warning: address of local variable 'str' returned [enabled by default]

$ ./a.exe
string0 == string1 is true
string1 == string2 is false
test_string1: string
test_string1: string
test_string2: string
test_string2: string
test_string3: string
test_string3: abc12345YP@