C Tutorial/Function/Function Parameter — различия между версиями
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Текущая версия на 10:32, 25 мая 2010
Содержание
Call by reference
#include<stdio.h>
main ( )
{
int i;
i = 0;
printf (" The value of i before call %d \n", i);
f1 (&i);
printf (" The value of i after call %d \n", i);
}
f1(int *k)
{
*k = *k + 10;
}The value of i before call 0 The value of i after call 10
Cube a variable using call-by-reference with a pointer argument
#include <stdio.h>
void cubeByReference( int *nPtr );
int main()
{
int number = 5;
printf( "The original value of number is %d", number );
cubeByReference( &number );
printf( "\nThe new value of number is %d\n", number );
return 0;
}
void cubeByReference( int *nPtr )
{
*nPtr = *nPtr * *nPtr * *nPtr; /* cube *nPtr */
}The original value of number is 5 The new value of number is 125
Cube a variable using call-by-value
#include <stdio.h>
int cubeByValue( int n );
int main()
{
int number = 5;
printf( "The original value of number is %d", number );
/* pass number by value to cubeByValue */
number = cubeByValue( number );
printf( "\nThe new value of number is %d\n", number );
return 0;
}
int cubeByValue( int n ) {
return n * n * n;
}The original value of number is 5 The new value of number is 125
Parameter passing
Information can be passed into function.
#include<stdio.h>
main ( )
{
int i;
i = 0;
printf (" The value of i before call %d \n", i);
f1 (i);
printf (" The value of i after call %d \n", i);
}
f1 (int k)
{
k = k + 10;
}The value of i before call 0 The value of i after call 0
Pass variables to function
#include <stdio.h>
float average(float x, float y)
{
return (x + y)/2.0f;
}
int main(void)
{
float value1 = 1.0F;
float value2 = 2.0F;
float value3 = 0.0F;
value3 = average(value1, value2);
printf("\nThe average is: %f\n", value3);
return 0;
}The average is: 1.500000
Use pointer as function parameter
#include <stdio.h>
int change(int* pnumber); /* Function prototype */
int main(void)
{
int number = 10;
int *pnumber = &number;
int result = 0;
result = change(pnumber);
printf("\nIn main, result = %d\tnumber = %d", result, number);
return 0;
}
int change(int *pnumber)
{
*pnumber *= 2;
printf("\nIn function change, *pnumber = %d\n", *pnumber );
return *pnumber;
}In function change, *pnumber = 20
In main, result = 20 number = 20
