C Tutorial/printf scanf/scanf Basics — различия между версиями

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Текущая версия на 10:32, 25 мая 2010

Pass pointer argument to scanf

#include <stdio.h>
int main(void)
{
  int value = 0;
  int *pvalue = NULL;
  pvalue = &value;                    /* Set pointer to refer to value  */
  printf ("Input an integer: ");
  scanf(" %d", pvalue);              /* Read into value via the pointer */
  printf("\nYou entered %d\n", value);
  return 0;
}
Input an integer: string
     
     You entered 0

Reading and discarding characters from the input stream

#include <stdio.h>
int main()
{ 
   int month1; 
   int day1;   
   int year1;  
   int month2; 
   int day2;   
   int year2;  
   
   printf( "Enter a date in the form mm-dd-yyyy: " );
   scanf( "%d%*c%d%*c%d", &month1, &day1, &year1 );
   printf( "month = %d  day = %d  year = %d\n\n", month1, day1, year1 );
   
   printf( "Enter a date in the form mm/dd/yyyy: " );
   scanf( "%d%*c%d%*c%d", &month2, &day2, &year2 );
   
   printf( "month = %d  day = %d  year = %d\n", month2, day2, year2 );
   return 0; 
}
Enter a date in the form mm-dd-yyyy: 01-01-2001
month = 1  day = 1  year = 2001
Enter a date in the form mm/dd/yyyy: 01/01/2002
month = 1  day = 1  year = 2002

scanf

The scanf function: read information from a standard input device (keyboard).


scanf("conversion specifier", variable);

The conversion specifier argument tells scanf how to convert the incoming data.

  1. scanf starts with a string argument and may contain additional arguments.
  2. Additional arguments must be pointers.
  3. scanf returns the number of successful inputs.

Common Conversion Specifiers Used with Scanf

Conversion Specifier Description %d Receives integer value %f Receives floating-point numbers %c Receives character

The scanf placeholders

d, i Used for signed integers; the expected argument should be a pointer to int.


#include <stdio.h>
main()
{
    int i = 0;
    int k;
    printf("input an integer:\n");
    i=scanf("%d",&k);
    printf("total values inputted %d\n",i);
    printf("The input values %d\n",k);
}
input an integer:
      3
      total values inputted 1
      The input values 3

Use scanf to get input from a standard input device, such as a keyboard

In scanf, you have to specify the address of a variable, such as &i, &j, and a list of format specifiers (%d). The number of format specifiers must be the same as the number of variables.


#include <stdio.h>
main(){
  int i,j,k;
  printf("Input two integers and press Enter to comfirm:");
  scanf("%d%d",&i,&j);
  k = i + j;
  printf("sum of two numbers is %d \n",k);
}
Input two integers and press Enter to comfirm:223
     2
     sum of two numbers is 225

Using an inverted scan set

#include <stdio.h>
int main()
{ 
   char z[ 9 ]; 
   
   printf( "Enter a string: " );
   scanf( "%[^aeiou]", z ); 
   printf( "The input was \"%s\"\n", z );
   return 0;
}
Enter a string: string
The input was "str"

Using Scanf to Receive Input from a User

#include <stdio.h>
main(){
  int iOperand1 = 0;
  int iOperand2 = 0;
  printf("\nEnter first operand: ");
  scanf("%d", &iOperand1);
  printf("Enter second operand: ");
  scanf("%d", &iOperand2);
  printf("The result is %d\n", iOperand1+iOperand2);
}
Enter first operand: 1
      Enter second operand: 2
      The result is 3
Источник — «http://cppe.ru/index.php?title=C_Tutorial/printf_scanf/scanf_Basics&oldid=3775»