3种方法交换两个整数（不创建临时变量）+输出一组数据最大值+简单排序+最大公约数

交换两个整数：
第一种：
int a = 6;
int b = 8;
int t = 0;
t = a;
a = b;
b = t;
printf(“a = %d b = %d\n”, a, b);
后两种不创建临时变量
第二种：
int a = 6;
int b = 8;
a = a + b;
b = a - b; //b = 6
a = a - b; //a = 8;
printf(“a = %d b = %d\n”, a, b);
第三种：

int a = 6; 	
int b = 8; 	
a = a ^ b; 	
b = a ^ b;  //b = 6 	
a = a ^ b;  //a = 8 	
printf("a = %d b = %d\n", a, b); 

输入一组数据，并输出这组数据的最大值：

#include<stdio.h> /* 输入一组数据，输出最大值 */
int max(int a[]) {
int max = 0;
for (int i = 0; i < 10;i++) {
if (max < a[i]) {
max = a[i];
}
}
return max;
}
int main() {
int a[10];
printf(“Please input 10 numbers in the screen:\n”);
for (int i = 0; i < sizeof(a)/4; i++) {
scanf("%d", &a[i]);
}
printf(“The max number of these datas is %d\n”, max(a)); return 0;
}

输入3个数，按从大到小的顺序输出：

#include<stdio.h> /* 输入3个数，按从大到小的顺序输出 */
int main() {
int a = 0, b = 0, c = 0;
int t = 0;
printf(“Please input 3 numbers (every number is separated with space:\n”); scanf("%d %d %d", &a, &b, &c);
if (a < b) {
t = a;
a = b;
b = t;
}
if (a < c) {
t = a;
a = c;
c = t;
}
if (b < c) {
t = b;
b = c;
c = t;
}
printf(“The 3 numbers from big to small: %d %d %d\n”, a, b, c); return 0;
}

输入两个数，求这两个数的最大公约数：

#include<stdio.h> /* 求两个数的最大公约数 */
int main() {
int a = 0, b = 0;
int judge = 0;
printf(“Please input 2 numbers:”);
scanf("%d %d", &a, &b);
while ((judge = a % b) != 0) {
a = b;
b = judge;
}
printf(“The max common divisor is : %d\n”, b);
return 0;
}