自定义加减乘除取模函数并调用
#include <stdio.h>
// add
int add(int a, int b)
{
int c = a + b;
return c;
}
// subtract
int sub(int a, int b)
{
int c = a - b;
return c;
}
// multiply
int mul(int a, int b)
{
int c = a * b;
return c;
}
// divide
int div(int a, int b)
{
int c;
if (b != 0)
c = a / b;
else
printf("b can't be 0!\n");
return c;
}
// mode
int mod(int a, int b)
{
int c;
if (b != 0)
c = a % b;
else
printf("b can't be 0!\n");
return c;
}
int main(int argc, const char *argv[])
{
int a, b;
printf("Please input 2 number:");
scanf("%d%d", &a, &b);
printf("a + b = %d\n", add(a, b));
printf("a - b = %d\n", sub(a, b));
printf("a * b = %d\n", mul(a, b));
printf("a / b = %d\n", div(a, b));
printf("a %% b = %d\n", mod(a, b));
return 0;
}实现数组的连加连减
#include <stdio.h>
#define N 10
int arr_add(int num[], int len)
{
int i, sum = 0;
for (i = 0; i < len; i++)
sum += num[i];
return sum;
}
int arr_sub(int num[], int len)
{
int i, sub = num[0];
for (i = 1; i < len; i++)
sub -= num[i];
return sub;
}
int main(int argc, const char *argv[])
{
int a[N] = {0}, i = 0;
int sum, sub;
for (i = 0; i < N; i++)
{
a[i] = i + 10;
printf("a[%d] = %d\n", i, a[i]);
}
printf("Reverse output:\n");
// reverse output
for (i = N - 1; i >= 0; i--)
printf("a[%d] = %d\n", i, a[i]);
sum = arr_add(a, N);
sub = arr_sub(a, N);
printf("arr sum: %d, arr sub:%d\n", sum, sub);
return 0;
}编程判断3人中谁的年龄最大，并打印最大者的年龄
#include <stdio.h>
int age_cmp(int a, int b)
{
if (a > b)
return a;
else
return b;
}
int main(int argc, const char *argv[])
{
int Tom, Bob, Mike;
printf("Please input 3 ages:");
scanf("%d %d %d", &Tom, &Bob, &Mike);
printf("the oldest is %d\n", age_cmp(age_cmp(Tom, Bob), Mike));
return 0;
}求数值的绝对值
#include <stdio.h>
extern int myabs(int num);
int main(int argc, const char *argv[])
{
int a = 10;
int b = -5;
printf("%d abs is %d\n", a, myabs(a));
printf("%d abs is %d\n", b, myabs(b));
return 0;
}
int myabs(int x)
{
if (x >= 0)
{
return x;
}
else
{
return -x;
}
}判断3个数能否组成一个三角形，将其实现为一个函数，并调用
#include <stdio.h>
int is_triangle(int a, int b, int c)
{
if ((a <= 0) || (b <= 0) || (c <= 0))
{
printf("Usage: a:%d, b:%d, c:%d\n", a, b ,c);
return(-1);
}
if (((a + b) > c) && ((a + c) > b) && ((b + c) > a))
return 1;
else
return 0;
}
int main(int argc, const char *argv[])
{
int a, b, c;
int result;
printf("Please input 3 number as triangle:");
scanf("%d %d %d", &a, &b, &c);
result = is_triangle(a, b, c);
if (result == 1)
printf("a = %d, b = %d, c = %d can found a triangle!\n", a, b, c);
else if (result == 0)
{
printf("a = %d, b = %d, c = %d can not found a triangle!\n", a, b, c);
}
else
printf("Invariable input!\n");
return 0;
}求1-100之间的素数，将其实现为函数，并调用
#include <stdio.h>
int is_prime(int n)
{
int i;
for (i = 2; i < n; i++)
{
if ((n % i) == 0)
break;
}
if (i == n)
return 1;
else
return 0;
}
int main(int argc, const char *argv[])
{
int i;
for (i = 1; i <= 100; i++)
{
if (!is_prime(i))
continue;
printf("%d\n", i);
}
return 0;
}使用递归函数求和
/*
* filename: add_recursion.c
*
* function: add form 1 to n with recursion
*
* author: YourName
*
* version: 0.1
*
* date: 2011-10-27
*
*/
#include <stdio.h>
int sum(int n)
{
if (0 == n)
return 0;
else
return n + sum(n-1);
}
int main(int argc, const char *argv[])
{
int n;
printf("Please input a number:");
scanf("%d", &n);
printf("1+2+...+%d = %d\n", n, sum(n));
return 0;
}