atoi命令中的分段错误

Question

I have the following code:

int main(int argc, char *argv[])
{
    int value,direction=0;
    char c;
    printf ("go\n");
    while((c = getopt(argc, argv, "wr:")) != -1) {
        printf ("go\n");
        printf("%c\n",c);
        switch(c) {
        case 'w':
            printf ("go\n");
            value=atoi(optarg);
            printf ("go\n");
            printf("The input value is %x",value);
            direction=1; //1 for write
            break;
        case 'r':
            direction=0; // 0 for read
            break;
        default:
            printf("invalid option: %c\n", (char)c);
            usage();
            return -1;
        }

    }
}

Now when i run the program by writing

 ./spicode.out -w 25

I need to pick the 25 after w using optarg, but its producing a segmentation fault.

What am i doing wrong?

Answer 1

您应该在命令行选项之间放置冒号。

   c = getopt(argc, argv, "w:r")

Answer 2

From gnu.org :

An option character in this string can be followed by a colon (':') to indicate that it takes a required argument

Therefore wr: becomes w:r