CODEWITHSUNDEEP
carraysstringfor-loop
sam whittle
sam whittle

Reputation: 111

char array printing 1 char short of what I assigned

I am trying to create a character array with X number of characters.

I need the first X-1 characters to be spaces and I need the Xth character to be an *.

I have written the following:

int i = 0;
int X = 5;
char spaces[X]; //In this case X is 5 so the array should have indexes 0 - 4
for(i = 0; i < X; i++) {
    spaces[i] = '*'; //I start by setting all 5 char's equal to '*'
    printf("spaces = '%s'\n", spaces); //This was to make sure it ran the correct # of times
}

The output of this segment is the following, the 'gh' is different every time:

spaces = '*gh'
spaces = '**h'
spaces = '***'
spaces = '****'
spaces = '****'

why does spaces only grow to 4 instead of 5 characters? Shouldn't spaces[4] = '*'; have been called?

After setting the whole string equal to '*' I run a second for loop:

for(i = 0; i < X-1; i++) {
    spaces[i] = ' ';
}

which should then set everything but the Xth character equal to ' ', but since the string is acting like its only X-1 characters long, the whole thing is set to spaces and it comes out like this

spaces = '    ';

4 spaces, when I need 4 spaces followed by an *.

Upvotes: 0

Views: 60

Answers (2)

knils
knils

Reputation: 115

In order to set first X-1 characters to be spaces and the Xth character to be an . This will always have the last character a ''

for(i = 0; i < X-1; i++) {
    spaces[i] = ' ';
    spaces[i+1] = '*'; 
    printf("spaces = '%s'\n", spaces); 
}

Upvotes: 0

Stephan Lechner
Stephan Lechner

Reputation: 35154

You are missing the string termination character \0, which is needed once you want to print your array as a string using printf("%s",...). So make your array one item larger than the items you want to print, and initialize it with 0, such that everything you write into the array will at the end be a valid string. Otherwise you yield undefined behaviour:

int main (void)
{
#define X 5

    int i = 0;
    char spaces[X+1] = { 0 };
    for(i = 0; i < X; i++) {
        spaces[i] = '*'; 
        printf("spaces = '%s'\n", spaces); 
    }
}

Upvotes: 1

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