无法将命令行参数复制到C中的字符指针 [英] cannot copy command line argument to character pointer in C

问题描述

我正在获取要复制到字符指针的命令行参数。

I am taking command line argument which I am copying to my character pointer. but its giving me an error.

int main(int argc, char *argv[])
{
    char *cmdarg;
    if(argc>1)
            strcpy(cmdarg, argv[1]);
    else
            cmdarg = NULL;
    return 0;
}

这给了我

Segmentation fault (core dumped)

推荐答案

您没有在要复制表达式 argv [1] 指向的参数的地方分配内存。

You did not allocate memory where you are going to copy the argument pointed to by the expression argv[1].

尝试以下操作

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

int main(int argc, char *argv[])
{
    char *cmdarg = NULL;

    if( argc > 1 )
    {
        cmdarg = malloc( strlen( argv[1] ) + 1 );
        if ( cmdarg != NULL ) strcpy( cmdarg, argv[1] );
    }

    // ...    Some other code

    free( cmdarg );

    return 0;
}

如果您只想存储指针的值 argv [1] 然后写

If you want just to store the value of the pointer argv[1] then write

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

int main(int argc, char *argv[])
{
    char *cmdarg = NULL;

    if( argc > 1 )
    {
        cmdarg = argv[1];
    }

    // ...    Some other code

    return 0;
}

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