C Tutorial/printf scanf/scanf Basics
Содержание
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.
- scanf starts with a string argument and may contain additional arguments.
- Additional arguments must be pointers.
- 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
