c - 字符串在 Visual Studio 和 gcc 中的打印方式不同

Question

我用Visual Studio 2012创建了一个简单的项目，代码编译成功，运行，打印结果如我所料(水果名称:apple)。当我尝试用 gcc 编译相同的代码时，打印输出看起来不同(水果名称是:apple')。 ' 来自哪里？下面是代码:

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdlib.h> 

char * getCharValue(char line[]){
    char *pch = strchr(line, '='); //find where the equal sign is in the line
    char *pch1 = strchr(line, '\0'); // find the index of the end of the line
    char *info = (char *) malloc(sizeof(char) * (pch1-pch-4));
    info[pch1-pch-5] = '\0';
    // copy the value to a new array then return the new char;
    memcpy(info, &line[pch-line+3], pch1-pch-5);
    return info;
}

int main()
{   
    char nameFileName[] = "Name.txt";       //register file name;
    char *nameValue;
    FILE *fid = fopen(nameFileName, "r");
    if (fid != NULL){   
        char line[150];
        while(fgets(line, sizeof(line), fid) != NULL){   
            //if this line is not empty or a comment line
            if ((strncmp(line, "//", 2) != 0) && (line[0] != '\n')) {   
                if (strstr(line, "fruit_name") != NULL){
                    nameValue = getCharValue(line);
                    printf("The fruit name is: %s\n", nameValue);
                }
            }
        }
    }
    else{
        printf("Can not find the input file.");
        exit(-1);
    }
    fclose(fid);
    return 0;
}

文本文件仅包含 1 行:

fruit_name           = 'apple'

我的代码有什么问题吗？为什么它与 Visual Studio 一起工作没有问题，但使用 gcc 却不能产生正确的结果？

Answer 1

您已使用 ' 进行分隔，但从不检查它们，也从不检查格式错误的文件。这是我的修订版。请注意，我不转换 malloc() 也不使用 sizeof(char)。

#include <stdio.h>
#include <string.h>
#include <stdlib.h> 

char * getCharValue(char line[]){
    char *pch, *pch1, *pch2, *info;
    int len;
    pch = strchr(line, '=');  // find where the equal sign is in the line
    if (pch == NULL)
        return NULL;
    pch1 = strchr(pch+1, '\''); // find the following quote mark
    if (pch1 == NULL)
        return NULL;
    pch2 = strchr(pch1+1, '\''); // find the following quote mark
    if (pch2 == NULL)
        return NULL;
    // copy the value to a new array then return the new char;
    len = pch2 - pch1 - 1;
    if (len <= 0)
        return NULL;
    info = malloc(len+1);
    memcpy(info, pch1+1, len);
    info[len] = '\0';
    return info;
}

int main()
{   
    char nameFileName[] = "Name.txt";       //register file name;
    char *nameValue = NULL;   //default
    FILE *fid = fopen(nameFileName, "r");
    if (fid != NULL){   
        char line[150];
        while(fgets(line, sizeof(line), fid) != NULL){   
            //if this line is not empty or a comment line
            if ((strncmp(line, "//", 2) != 0) && (line[0] != '\n')) {   
                if (strstr(line, "fruit_name") != NULL){
                    nameValue = getCharValue(line);
                    if (nameValue == NULL)
                        printf("The file was badly formatted\n");
                    else
                        printf("The fruit name is: %s\n", nameValue);
                }
            }
        }
    }
    else{
        printf("Can not find the input file.");
        exit(-1);
    }
    fclose(fid);
    free(nameValue);    // won't matter if it is NULL
    return 0;
}

程序输出

The fruit name is: apple