C++, scanf 에서 float 사용하기

 

scanf에서 double 형으로 처리하려는 분들이 많으신데 %lf를 사용하면 double 형으로 받을 수 있습니다.

 

 

#include "stdafx.h"

 

int _tmain(int argc, _TCHAR* argv[])

{

    int a;

    double b,c,d;

    printf("키는?");

    scanf("%d",&a);

 

    printf("체중은?");

    scanf("%lf",&b);

 

 

    c = (a-100)*0.9;

    d = b-c;

    printf("키가%d 인사람의표준체중은%.1lf 이며, 현재체중과표준체중의차이는%.1lfKg이다\r\n",a,c,d);

 

    return 0;

}

 

 

 

   

 

 

double 대신 float 를 사용

 

 

#include "stdafx.h"

 

int _tmain(int argc, _TCHAR* argv[])

{

    int a;

    float b,c,d;

    printf("키는?");

    scanf("%d",&a);

 

    printf("체중은?");

    scanf("%f",&b);

 

 

    c = (a-100)*0.9;

    d = b-c;

    printf("키가%d 인사람의표준체중은%.1lf 이며, 현재체중과표준체중의차이는%.1lfKg이다\r\n",a,c,d);

 

    return 0;

}

 

 

float 를 double 형으로 변경하게 되면 아래처럼 원하는 결과를 얻을 수 있습니다.

 

 

 

 

 

scanf 함수 도움말

 

 

scanf 도움말을 참고해 보세요.~

 

 

int scanf ( const char * format, ... );

Read formatted data from stdin

Reads data from stdin and stores them according to the parameter format into the locations pointed by the additional arguments. The additional arguments should point to already allocated objects of the type specified by their corresponding format tag within the format string.

Parameters

format

C string that contains one or more of the following items:

  • Whitespace character: the function will read and ignore any whitespace characters (this includes blank spaces and the newline and tab characters) which are encountered before the next non-whitespace character. This includes any quantity of whitespace characters, or none.
  • Non-whitespace character, except percentage signs (%): Any character that is not either a whitespace character (blank, newline or tab) or part of a format specifier (which begin with a % character) causes the function to read the next character from stdin, compare it to this non-whitespace character and if it matches, it is discarded and the function continues with the next character of format. If the character does not match, the function fails, returning and leaving subsequent characters of stdin unread.
  • Format specifiers: A sequence formed by an initial percentage sign (%) indicates a format specifier, which is used to specify the type and format of the data to be retrieved from stdin and stored in the locations pointed by the additional arguments. A format specifier follows this prototype:

    %[*][width][modifiers]type

    where:

*

An optional starting asterisk indicates that the data is to be retrieved from stdin but ignored, i.e. it is not stored in the corresponding argument.

width

Specifies the maximum number of characters to be read in the current reading operation

modifiers

Specifies a size different from int (in the case of d, i and n), unsigned int (in the case of o, u and x) or float (in the case of e, f and g) for the data pointed by the corresponding additional argument:
h :
short int (for d, i and n), or unsigned short int (for o, u and x)
l :
long int (for d, i and n), or unsigned long int (for o, u and x), or double (for e, f and g)
L :
long double (for e, f and g)

type

A character specifying the type of data to be read and how it is expected to be read. See next table.


  • scanf type specifiers:

type

Qualifying Input

Type of argument

c

Single character: Reads the next character. If a width different from 1 is specified, the function reads width characters and stores them in the successive locations of the array passed as argument. No null character is appended at the end.

char *

d

Decimal integer: Number optionally preceded with a + or - sign.

int *

e,E,f,g,G

Floating point: Decimal number containing a decimal point, optionally preceded by a + or - sign and optionally folowed by the e or E character and a decimal number. Two examples of valid entries are -732.103 and 7.12e4

float *

o

Octal integer.

int *

s

String of characters. This will read subsequent characters until a whitespace is found (whitespace characters are considered to be blank, newline and tab).

char *

u

Unsigned decimal integer.

unsigned int *

x,X

Hexadecimal integer.

int *

additional arguments

The function expects a sequence of references as additional arguments, each one pointing to an object of the type specified by their corresponding %-tag within the format string, in the same order.
For each format specifier in the format string that retrieves data, an additional argument should be specified.
These arguments are expected to be references (pointers): if you want to store the result of a
fscanf operation on a regular variable you should precede its identifier with the reference operator, i.e. an ampersand sign (&), like in:

int n;
scanf ("%d",&n);

 

Return Value

On success, the function returns the number of items succesfully read. This count can match the expected number of readings or fewer, even zero, if a matching failure happens.
In the case of an input failure before any data could be successfully read,
EOF is returned.

 

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