Input and output of floating point data (C language)

Catalog

1 Input of floating point data

1.1  Single precision input

1.2  Double precision and long double precision

2 Floating point data output

2.1  The default output of floating point numbers

2.2  Specify the output format %m . n f

2.3  Output example

3 Case study  

3.1  Case study

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1 Input of floating point data

1.1  Single precision input

(1) Format 1

Format controller ：%f、%e、%g（ or %F、%E、%G）

Example ：float f1,f2;

scanf("%f%f",&f1,&f2); //%f for %e or %g

Such as the input ： 3.14159 and 5.3, The input format is ：

The correct sample 3.14159 5.3 // Default white space separation

The wrong sample ：3.14159 , 5.3

(2) Format 2

Change to the following form ：

scanf("f1=%f ,f2=%f ",&f1,&f2);

Enter examples correctly ： f1=3.14159 ,f2=5.3

1.2  Double precision and long double precision

double Controller ：%lf、%le、%lg etc. .

double d;

scanf("%lf",&d);

long double Controller :%Lf、%Le、%Lg etc. .

long double Ld;

scanf(“%Lf”,&Ld);

 

2 Floating point data output

2.1  The default output of floating point numbers

float、double Controller ：%f

float f=5.6f;

double d=314.159;

printf("f=%f,d=%f",f,d); // Can not write %F

VC++6.0 in , The default output is after the decimal point 6 position . The result is ：

f=5.600000,d=314.159000

2.2  Specify the output format %m . n f

Format Total seat width The fractional part Alignment mode

%m.nf m n Right

%-m.nf m n Left

%.nf There is no limit n Right

Default right alignment , rounding

2.3  Output example

float f1=3.14159f;

printf("f1=%.3f",f1);

Output results ： f1=3.142

printf("f1=%.0f",f1); Indicates that only integer parts are output .

Output results ： f1=3

3 Case study  

3.1  Case study

【 Case study 】 Enter the radius and height of the bottom circle of the cylinder from the keyboard , Calculate and input

Figure out the volume of the cylinder （ After decimal point 2 position ）.

#include<stdio.h>
const float PI=3.14f;
int main(void)
{
	float r,h,v;
	printf("Input radius and height:\n");
	scanf("r=%f,h=%f",&r,&h);
	v=PI*r*r*h;
	printf("volume=%.2f\n",v);
	return 0;
}