Why do strings get printed twice when using printf in C?

Question

My program asks the user to provide a string, which will be copied into an array of characters. Then, with a for loop, the program simply copies the elements of the first array into the second array.

int main() {

    int i;
    char string1[4], string2[4];

    // Get the first string
    printf("Insert your string: ");
    scanf("%s", string1);

    // Copy the values into the second array
    for (i = 0; i < 4; i++) {
        string2[i] = string1[i];
    }

    // Print the second string
    printf("%s", string2);
    return 0;
}

However, when I print the string using the printf() function the string gets printed twice.

Let's say I input the word

bars

The output will be

barsbars

Why is this happening?

Answer 1

char string1[4], string2[4];

4-element char array is not enough for 4-character strings. You need one more for the terminating '\0' character.