CODEWITHSUNDEEP
cstringpointers
Hana
Hana

Reputation: 613

Function that returns char *

I have a function that receives an int and returns a pointer to a string array:

char* DoSomething (int num);

But I don't understand how to deal with it in the main. Essentially I want to print the string I am getting from the function. But in the main I get a warning: assignment from incompatible pointer type. This is my main:

int main()
{
    int num = 12345;
    char* a;
    a = DoSomething(12345);
    return 0;
}

Updating. I didn't want to put a long code, but adding as per your request. The function is defined in a separate c file.

/* conver int to String */
char* IntToString (int num)
{
    int i;
    int sign = 1;
    int len;
    int begin = 0;
    char* str = malloc (sizeof(char)*30);  
    if (num<0)
    {
        sign = -1;
        num = num*(-1);
    }
    len = CountDigits(num);
    if (sign == -1)
    {
        str[0]='-'; 
        begin = 1;
    }
    int newLen = len;
    for (i=0; i<len; i++)
    {
        int digit;
        char digitChar;
        int modul;

        digit = num/(pow(10, newLen-1));
        digitChar = digit + ASCII_ZERO;
        str[i+begin] = digitChar;
        modul = pow(10, newLen-1);
        num = num % modul;
        newLen--;
    }
    return str;
}

Then in the main I am trying to call the function:

int main()
{
    int num = 12345;
    char* a;
    a = IntToString(12345);
    return 0;
}

Upvotes: 0

Views: 293

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726499

You get a warning because the function is defined after main, and lacks prototype.

Move the function to before main, or add this line:

char* DoSomething (int num);

Now the warning will be gone, and you would be able to print your string in a way that you prefer, for example

printf("%s\n", a);

Note 1: The string you are returning is not null terminated.

Note 2: Since you are using malloc in the function, you need to call free on the result in the main.

Upvotes: 4

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