Copying valid strings to 2d array in C

November 18, 2021

I am checking if a function returns true, it prints out valid strings according some other function I got. At the moment, it’s printing it out correctly but it is also printing empty lines which seem to correspond to the invalid strings.

How can I make these empty lines go away?

Here is my code:

int main()
{
    int i, count = 0;
    char input[10];
    char validStr[10][60] = {""};
    for (i = 0; i < 60; ++i){
        if(fgets(input,10, stdin) == NULL){
            break;
        }
        input[strcspn(input,"\n")] = '\0';
        if(checkIfValid(input)){
            memcpy(validStr[i],input,sizeof(input));
            count++;
        }
    }
    printf("%d\n",count);
    for (int j = 0 ; j < count; ++j){
        printf("%s\n",validStr[j]); 
    }
}

The count indicates it is printing only the valid strings but as you can tell by the pic it prints white lines.

Note: For various reasons the program needs to follow the current order so the output is printed after the first for loop.

Thanks in advance!

>Solution :

Instead of this:

    if(checkIfValid(input)){
        memcpy(validStr[i],input,sizeof(input));
        count++;
    }

This:

    if(checkIfValid(input)){
        memcpy(validStr[count],input,sizeof(input));
        count++;
    }

As others have pointed out in the comments, you want to safely secure that string copy. May I suggest:

    if(checkIfValid(input)){
        char* dst = validStr[count];
        size_t MAXLEN = 10;
        strncpy(dst, input, MAXLEN);
        dest[MAXLEN-1] = '\0';
        count++;
    }