CODEWITHSUNDEEP
carrays
MohammadM
MohammadM

Reputation: 27

Printing array partially in C

I am a newbie to C and want to print some special elements of an array. 

//Partial code here
    char aaa[18] ;
    int i = 0;
    while(i < 18) {
        aaa[i] = '#' ;
        printf("%c", aaa[i]) ;
        i = i + 4 ;    
   }

It's supposed to prints 4 # of aaa[0] ,aaa[4],aaa[8],aaa[12],aaa[16]. But it is not. It is printing them in a row like #####. But I don't want those .

Upvotes: 0

Views: 374

Answers (2)

user7881131
user7881131

Reputation:

I'm assuming you want to eventually print a string and get output like this

"#   #   #   #   #  "

minus the quotes.

You can do this by filling in a null-terminated string and then printfing that, like so:

// +1 for space for a null terminator
// = {0}; fills the array with 0s
char aaa[18+1] = {0};

// for loop is more idiomatic for looping over an array of known size
for (int i = 0; i < 18; i += 4) {
    // if the remainder of dividing i by 4 is equal to 0
    if (i % 4 == 0) {
        // then put a '#' character in the array at aaa[i]
        aaa[i] = '#';
    } else {
        // otherwise put a ' ' character in the array at aaa[i]
        aaa[i] = ' ';
    }
}

printf("%s", aaa);

Upvotes: 4

Tiago Cunha
Tiago Cunha

Reputation: 169

As you're adding 4 to the i variable in each cycle you're printing the positions 0, 4, 8, 12, 16 of the array consecutively.

If you want to print the vector with # as the 4*nth element you should do something like:

while( i < 18 ) 
{
  if( i % 4 == 0 )
  {
    aaa[i] = '#';
    printf("%c" ,aaa[i]);
  }
  else 
    printf(" "); // Assuming you want a space in between prints

  i++;
}

Upvotes: 3

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