ls command does not work in the Program written in C(shell script)

Question

void main() {
    char *args[MAX_LINE];
    char arg1[MAX_LINE/2] = "\0";
    char arg2[MAX_LINE/2] = "\0";
    printf("ubos>");
    fflush(stdout);
    fgets(arg1, sizeof(arg1), stdin);
    arg1[strlen(arg1) - 1] = '\0';
    fgets(arg2, sizeof(arg2), stdin);
    arg2[strlen(arg2) - 1] = '\0';

  abc:  
    printf("You typed: %s %s\n", arg1, arg2);
    fflush(stdin);
    args[0] = arg1;
    args[1] = arg2;
    args[2] = '\0'; 

    int i = 0;
    for (i = 0; i < MAX; i++) {
        printf("Vlue of arg[%d] =%s\n", i, args[i]);
    }

    if (strcmp(args[0], "ls") == 0) {
        execvp(args[0], args);
        goto abc;
    } else
    if (strcmp(args[0], "ps") == 0) {

    }

    printf("Something is not correct...\n");
    exit(0);
}

when I run this code with ls command this is the result. I don't know what is the problem with this code. When I run this code to execute another .c file it execute perfectly but when I try to use ls or ps command it does not let me use it and throws the error.

I have one more question why this goto does not working in this program .

ubos>ls

You typed: ls 
Vlue of arg[0] =ls
Vlue of arg[1] =
Vlue of arg[2] =(null)
ls: cannot access : No such file or directory

so here is my mistake and can you give me some advise on how to use exec command and its different types.

Answer 1

If they don't provide an argument, set that argument in args to 0 . Then ls won't receive an empty string as its first argument, it won't get any arguments at all.

args[0] = arg1;
if (strlen(arg2) == 0) {
    args[1] = 0;
} else {
    args[1] = arg2;
    args[2] = 0;
}

You also need to check for this in the loop that prints all the arguments.

for(i=0;i<MAX && arg[i];i++)
{
    printf("Value of arg[%d] =%s\n",i, args[i]);
}

Answer 2

if (strlen(arg2) == '\0')
    {
         args[0] = arg1;
         args[1] = '\0';
    } 
    else 
    {
        args[0] = arg1;
            args[1] = arg2;
            args[2] = 0;
    }
for(i=0;i<MAX && args[i];i++)
    {
            printf("Vlue of args[%d] =%s\n",i, args[i]);
    }

I was passing the blank space as the second argument. so it was showing me the error. Above code is the solution of my problem..