Getting Array Input From Command Line

Question

I am using the command line to get input of 3 floats separated by spaces. e.g. "1.234 5.678 9.012".

I am currently using:

float xyz[3] = {0}; scanf("%f", xyz); print(%f %f %f, xyz[0], xyz[1], xyz[2]);

However the output is "1.234000 0.000000 0.000000".

Expected output is "1.234000 5.678000 9.012000"

EDIT: I need to use floats instead of integers.

you are scanning a single float and printing 3 floats. try looping the scanf() thrice and look for the result — Raghu Srikanth Reddy
– Raghu Srikanth Reddy, Commented Oct 29, 2014 at 5:51

Paul Rooney · Accepted Answer · 2014-10-29 20:16:17Z

Maybe this

#include <stdio.h> int main(int argc, char** argv) { float vals[3]; printf("input 3 float values: "); int res = scanf("%f %f %f", &vals[0], &vals[1], &vals[2]); if(res == 3) { printf("read 3 floats %f %f %f\n", vals[0], vals[1], vals[2]); } else { printf("failed to read 3 float values\n"); } return 0; }

this line: if(res >= 0) fails to assure that 3 items were read. The line should be: if(res == 3)

Anbu.Sankar · Accepted Answer · 2014-10-29 05:57:03Z

2

If you use command line arguments , simply try like

#include<stdio.h> #include<stdlib.h> main(int c, char **v) { float xyz[3]={0}; xyz[0]=atof(v[1]); xyz[1]=atof(v[2]); xyz[2]=atof(v[3]); printf("%f %f %f\n",xyz[0],xyz[1],xyz[2]); }

answered Oct 29, 2014 at 5:57

Anbu.Sankar

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2 Comments

user3629249 Over a year ago

this is correct for what the OP stated they were actually doing.

Paul Rooney Over a year ago

This should check that c (conventionally argc) is at least 3 before proceeding with the atof calls, if its less than 3 segfault. @user3629249 I disagree that this is more in line with what the OP stated they were actually doing, they said they were using scanf.

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