Array of Strings to functions and use strcpy

Question

I have an array of n strings where n is not known at compilation time.

The real input is a giant string that I will splice, and add the parts to each position of the array.

In the example I've simulated a sentence with n=3 , but n can be any number.

void addWords(char *array[][300], int n) {
    char p[] = "Hello ";
    char p1[] = "World ";
    char p2[] = "!";

    strcpy(array[0],p);
    strcpy(array[1],p1);
    strcpy(array[2],p2);

    printf("%s%s%s\n",array[0],array[1],array[2]);

}


int main(int argc, char const *argv[])
{
    int n = 3;
    char array[n][300];

    addWords(array,3);

    return 0;
}

The code gives segmentation fault and I cannot identify the cause.

@BillLynch sorry, already edited main message, the error is segmentation fault — digolira2
– digolira2, Commented Sep 30, 2021 at 15:37
in printf("%s%s%s\n",p[0],p[1],p[2]); you're passing the wrong arguments to printf. "%s" format specifier expects a string, but you're passing a char. Do you mean that to be printf("%s%s%s\n",p0,p1,p2);? — yano
– yano, Commented Sep 30, 2021 at 15:37
When compiled, your code produces numerous warnings that are fairly concerning. gist.github.com/sharth/b55c8a02f42a42a53c45a6863b5b6e05 — Bill Lynch
– Bill Lynch, Commented Sep 30, 2021 at 15:39

Luca Polito · Accepted Answer · 2021-09-30 15:39:40Z

2

//void addWords(char *array[][300], int n) {
void addWords(char array[][300], int n) { // <== use `char array[][300]`
    char p[] = "Hello ";
    char p1[] = "World ";
    char p2[] = "!";

    strcpy(array[0],p);
    strcpy(array[1],p1);
    strcpy(array[2],p2);

    //printf("%s%s%s\n",p[0],p[1],p[2]);
    printf("%s%s%s\n",array[0],array[1],array[2]); // <== I think you meant `array` instead of `p`
}

answered Sep 30, 2021 at 15:39

Luca Polito

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2 Comments

digolira2 Over a year ago

but I want to modify the array in the main, this only works on the function subspace, doesnt it? once the addWords is finished, the array is gone.

Luca Polito Over a year ago

@digolira2 No, char array[][300] is already a pointer (because arrays decay to pointers), therefore when you modify array[0], you're modifying the same array that is in main. It's just like using char str[] as a function parameter in order to modify a given string.

4386427 · Accepted Answer · 2021-09-30 15:54:48Z

1

This

void addWords(char *array[][300],
              ^^^^^^^^^^^^^^^^^^

means

pass a pointer to an array containing 300 char pointers

What you want to say is

pass a pointer to an array containing 300 char

So all you need is:

void addWords(char *array[][300], --> void addWords(char array[][300],

answered Sep 30, 2021 at 15:54

4386427

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Comments

nvf · Accepted Answer · 2021-09-30 15:38:43Z

0

I see that you declared 'addWords' with argument of type "char *array[][300]", but pass value of type "char array[n][300]". Different types.

answered Sep 30, 2021 at 15:38

nvf

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