Pls explain why this code is not going to work..

Question

1.00/5 (3 votes)

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Is %f not a format specifier for double? I have seen a couple of times that it is..please Explain........................

What I have tried:

C++

#include<stdio.h>
#include<conio.h>
void main()
{
   double d;
   scanf("%f",&d);
   printf("%f",d);
   getch();

}

Posted 8-Mar-17 4:16am

Member 13039393

Updated 8-Mar-17 5:27am

PIEBALDconsult

v4

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OriginalGriff · Accepted Answer · 2017-03-08T04:37:00

Solution 1

%f is the format code for a float, not a double. Since a double is twice the size of a float, when you read a float value into the memory for a double, the value you get is not correct.
Try %lf instead.

Posted 8-Mar-17 4:37am

OriginalGriff

Comments

Richard MacCutchan 8-Mar-17 11:26am

Interesting, I wonder why it is not coerced to a double?

OriginalGriff 8-Mar-17 14:09pm

Because it's a void pointer when it gets to the function - scanf doesn't know you passed it a pointer to a double, and you specifically asked for a float. Just like you can pass a int pointer to a %s scanf (and blow the stack!)

Richard MacCutchan 8-Mar-17 15:47pm

Duh, my stupid question.

CPallini 8-Mar-17 16:29pm

5.