CODEWITHSUNDEEP
carraysloopsfor-loop
Aldiandya Irsyad Nur Farizi
Aldiandya Irsyad Nur Farizi

Reputation: 48

Inputting value on 2D Float arrays with for loops

I'm trying to make a 2D array that has 2 column and some row. The first column is inputted by using scanf is the radius, while the second column are dependent on the first column is the area.

I already tried to leave them out of loops (manual input) then output them immediately but somehow only the last and first input are correct

#define circlecol 1
#define circlerow 1

int main() {
    float circles[circlerow][circlecol];
    for(int x = 0; x <= circlerow; x++) {
        scanf("%f", &circles[x][0]);
        circles[x][1] = 3.14*circles[x][0]*circles[x][0];
    }`

With the input of 8 and 3 I expected this to be the output

Your Circle: 8.000000 200.960000 3.000000 28.260000

But I get this instead

Your Circle: 8.000000 0.000000 0.000000 28.260000

The format was

Your Circle: [0][0] [0][1] [1][0] [1][1]

Upvotes: 3

Views: 67

Answers (2)

gsamaras
gsamaras

Reputation: 73366

Change this:

for(int x = 0; x <= circlerow; x++)

to this:

for(int x = 0; x < circlerow; x++)

since array indexing starts from 0 and ends at size of array - 1.

Similarly, you would do for(int j = 0; j < circlecol; j++).

In general, if an array is declared as:

array[rows][cols]

then its dimensions are rows x cols. array[0][0] is the element in the 1st row and 1st column, and array[rows - 1][cols - 1] is the element in the last column and in the last row.

Minimal complete example:

#include <stdio.h>

#define circlecol 1
#define circlerow 1

int main(void) {
  float circles[circlerow][circlecol];
  for(int x = 0; x < circlerow; x++) {
    scanf("%f", &circles[x][0]);
    circles[x][1] = 3.14*circles[x][0]*circles[x][0];
  }

  for(int i = 0; i < circlerow; i++)
    for(int j = 0; j < circlecol; j++)
      printf("%f", circles[i][j]);
  return 0;
}

Upvotes: 1

Vlad from Moscow
Vlad from Moscow

Reputation: 310980

This array

float circles[circlerow][circlecol];

in fact is declared as

float circles[1][1];

that is it has one row and one column that is only one element that can be accessed using expression circle[0][0].

It seems you mean the following

#define circlecol 2
#define circlerow 2

int main( void ) {
    float circles[circlerow][circlecol];
    for(int x = 0; x < circlerow; x++) {
        scanf("%f", &circles[x][0]);
        circles[x][1] = 3.14*circles[x][0]*circles[x][0];
    }
}

That is the array shall have two rows and two columns.

Upvotes: 0

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