Download void f(int x)

Tutorial #6
Summer 2005
functions
<type>
{
body
}
<name>( parameters list )
Max function
int max(int a, int b)
{
if (a > b)
return a;
return b;
}
Max function
#include <stdio.h>
int main()
{
int x, y;
scanf("%d%d", &x, &y);
printf("max = %d\n", max(x, y));
return 0;
}
Max function
int max(int a, int b)
{
return (a > b ? a : b);
}
Max function
void max(int a, int b)
{
if (a > b)
{
printf("%d > %d\n", a, b);
return ;
}
if (b > a)
{
printf("%d > %d\n", b, a);
return ;
}
printf("%d = %d\n", a, b);
}
Max function
void max(int a, int b)
{
if (a > b)
printf("%d > %d\n", a, b);
else if (b > a)
printf("%d > %d\n", b, a);
else
printf("%d = %d\n", a, b);
}
absolute
int absolute(int x)
{
return (x >= 0 ? x : -x);
}
absolute
int absolute(int x)
{
return (x >= 0 ? x : -x);
}
Triangle area
double triangle_area(double width,
double height)
{
double area = width * height / 2;
return area;
}
Triangle area
double triangle_area(double width,
double height)
{
return (width * height / 2);
}
messages
void messages(int i)
{
switch(i)
{
case 0 : printf("first message\n");
break;
case 1 : printf("second message\n");
break;
case 2 : printf("third message\n");
}
}
power
double power(double x, int y) /* y >= 0 */
{
double res;
for (res = 1; y > 0; y--)
res *= x;
return res;
}
power
double power(double x, int y) /* y >= 0 */
{
double res = 1;
for(; y > 0; y--)
res *= x;
return res;
}
What happens here?
void f(int x)
{
x++;
}
int main()
{
int x = 5;
f();
printf(“x = %d\n”, x);
return 0;
}
Arrays - Counting
int count(int arr[], int n, int val)
{
int i, cnt = 0;
for (i = 0; i < n; i++)
if (arr[i] == val)
++cnt;
return cnt;
}
Arrays - Assignments
void f(int arr[], int n)
{
for(i = 0; i < n; i++)
arr[i] = val;
}
Programs
#include <stdio.h>
#include <stdlib.h>
int mult(int, int);
int power(int, int);
void power_table(int, int);
int main()
{
int base, power;
printf("Enter base and power of the power table :");
if (scanf("%d%d", &base, &power) < 2)
{
printf("Input Error");
return 1;
}
power_table(base, power);
return 0;
}
mult
int mult(int x, int y) /* returns x*y */
{
int res = 0;
for (; y > 0; y--)
res += x;
return res;
}
Power table
void power_table(int n, int k)
{
int i, j ;
for (i = 1; I <= k; i++)
{
for (j = 1; j <= n; j++)
printf("%-5d",power(j, i));
putchar('\n');
}
return ;
}
Power
int power(int x, int y) /* returns x to the
power of y */
{
int res = 1;
for (; y > 0; y--)
res = mult(res, x);
return res;
}
Variables
Scope
 Static
 Global

scope
#include <stdio.h>
int main()
{
int x = 10, y = 15;
{
int x = 20;
printf(x  %d, y = %d\n, x++, y++);
}
printf(x  %d, y = %d\n, x, y);
return 0;
}
scope
#include <stdio.h>
int main( void )
{
int count = 1;
for ( ; count <= 5; count++)
{
int count = 1;
printf(“%d\n”, count);
}
return 0 ;
}
scope
#include <stdio.h>
int main( void )
{
int count = 1;
while (count <= 5)
{
int count = 1;
printf(“%d\n”, count);
count++;
}
return 0 ;
}
scope
int main()
{
int a = 1, b = 2, c = 3;
printf(%3d %3d %3d\n, a, b, c);
{
int b = 4; double c = 5.0;
printf(%d %d %f\n, a, b, c);
a  b;
{
int c;
c  b;
printf(%d %d %d\n, a, b, c);
}
printf(%d %d %f\n, a, b, c);
}
printf(%d %d %d\n, a, b, c);
return 0;
}
static
#include <stdio.h>
void f(void)
{
static int cnt = 1;
printf(%d , cnt++);
}
int main()
{
int i;
for(i = 0; i < 5; ++i)
f();
for(i = 0; i < 5; ++i)
f();
return 0;
globals
#include <stdio.h>
int x = 20, y;
void f1(int x)
{
printf(x = %d y = %d\n, x, y);
x = y = 10;
}
void f2(int y)
{
printf(x = %d y = %d\n, x, y);
x = y = 15;
}
int main()
{
y = 5;
f1(20);
f2(y);
printf(x = %d y = %d\n, x, y);
return 0;
}
fun
#include <stdio.h>
int x = 5, y = 6, z = 7;
void printvals(int a, int b, int c,
int x, int y ,int z)
{
printf(a = %d b = %d c = %d x = %d”
“ y = %d z = %d, a, b, c, x, y, z);
}
void oof(int a, int b, int c)
{
int x;
static int z;
printvals(a, b, c, x, y, z);
x = a;
z = x;
y++;
{
int a;
a = x; b = y; c = z;
printvals(a, b, c, x, y, z
}
printvals(a, b, c, x, y, z);
}
int main()
{
int a = 0;
x = 1; y = 2; z = 3;
oof(7, 8, 9);
x++; y++; z++;
oof(x, y, z);
return 0 ;
arrays
#include <stdio.h>
int main( void )
{
int a[3];
...
return 0 ;
}
a[0]
a[1]
a[2]
arrays
#include <stdio.h>
int main( void )
{
int a[3][5];
...
return 0 ;
}
<type>
0
0
1
2
3
a[0][0]
1
2
<name>[rows][columns] ;
a[1][3]
4
arrays
#include <stdio.h>
int main( void )
{
int a[3][5];
...
return 0 ;
}
0
0
1
2
3
4
0
1
2
1
2
arrays
#include <stdio.h>
int main( void )
{
int a[3][5], i, j;
0
for (i = 0; i < 3; i++)
1
for (j = 0; j < 5; j++)
scanf(%d”, &a[i][j]);
2
return 0 ;
}
0
1
0
1
2
3
2
4
arrays
#include <stdio.h>
int main( void )
{
int a[3][5], i, j;
0
for (j = 0; j < 5; j++)
for (i = 0; i < 3; i++)
1
scanf(%d”, &a[i][j]);
2
return 0 ;
}
0
1
0
1
2
3
2
4
arrays
#include <stdio.h>
int main( void )
{
int a[3][5], j, k, sum = 0 ;
for (j = 0; j < 3; j++)
for (k = 0; k < 5; k++)
scanf(%d”, &a[j][k]);
for (j = 0; j < 3; j++)
for (k = 0; k < 5; k++)
sum += a[j][k];
printf(The sum is : %d\n, sum) ;
return 0 ;
}
arrays
#include <stdio.h>
#define N 3
int main( void )
{
int matrix[N][N], j, k, sum = 0;
for (i = 0; i < N; i++)
for (j = 0; j < N; j++)
matrix[i][j] = i + j;
for (i = 0; i < N; i++)
{
for (j = 0; j < N; j++)
printf(%d “, matrix[i][j]);
printf(\n) ;
}
return 0;
}
typedef
typedef double scalar ;
typedef int length;
int main( void )
{
double a, b;
scalar c, d;
int i, j;
length k, l;
}
typedef
#include <stdio.h>
typedef scalar matrix[N][M] ;
#define
N
10
typedef vector matrix[N] ;
#define
M
20
typedef double scalar ;
typedef scalar vector[M] ;
typedef scalar matrix[N][M] ;
int main( void )
{
vector a, b; /* a & b are both arrays */
matrix mat; /* mat is a two-dimensions
array NM */
}