Thread: Help with Arrays :-)

Hi I would like to know how I can use a 2d array for instance to input some variable for instance ...........


I need 4 columns and a definable amount of rows

Person ID........... Wage...........Sex............Age
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thanks

Greg !!!

#define NUM_COLS 4 /* Person ID, Wage, Sex, Age */
#define NUM_ROWS 10 /* definable amount of rows */
int twod_array[NUM_ROWS][NUM_COLS];

but I need the user to be able to define the number of rows not .... to actually state it in the c source file .... if u understand what I mean :-)

Well if the number of columns is constant, then do this

Code:

#include <stdio.h>
#include <stdlib.h>

typedef int row_t[4];

int main ( ) {
    int    (*aptr)[4];
    row_t  *twod;
    int     nrows = 100;    // or user input
    int     r, c;

    aptr = malloc( nrows * sizeof(int[4]) );
    twod = malloc( nrows * sizeof(row_t) );
    for ( r = 0 ; r < nrows ; r++ ) {
        for ( c = 0 ; c < 4 ; c++ ) {
            aptr[r][c] = 0;
            twod[r][c] = 0;
        }
    }

    free( aptr );
    free( twod );
    return 0;
}

The only difference between aptr and twod is readability - the choice is yours.

that code brings up 2 error warnings in vis studio ....... is it meant to be adapted............ ? thanks for your help :-)

> is it meant to be adapted
NO!

It's meant to be compiled as C and not C++

Either write in C or write in C++, and name your files appropriately.

lol uppss forgot bout that ! thanks works fine ....... just need to know how to use the scanf command to enter data into the array i.e. row1 column1 row1 column2 etc...... oh is there a way I can make it so that after filling a row eg all 4 colums contain data I can make it ask if the user wishes to add more data or finish the input ?