C 语言流程控制与循环

1.if 语句

#include <iostream>

int main() {
int32_t a = 8;
int32_t b = 6;

if (a > b) {
printf("Max num is a, %d\n", a);
} else {
printf("Max num is b, %d\n", b);
}

int32_t score = 90;
if (score > 80) {
printf("Fine\n");
} else if (score >= 60) {
printf("OK\n");
} else {
printf("Fail\n");
}

return 0;
}

2.switch 语句

#include <iostream>

#define UP 1
#define DOWN 2
#define LEFT 3
#define RIGHT 4

int main() {
int32_t dir = 1;
switch (dir){
case UP:
printf("Go UP\n");
break;
case DOWN:
printf("Go DOWN\n");
break;
case LEFT:
printf("Go LEFT\n");
break;
case RIGHT:
printf("Go RIGHT\n");
break;
default:
printf("Dir unknow\n");
}
return 0;
}

3.goto 语句

#include <iostream>

int main() {

//    label:
//    printf("100\n");
//    printf("101\n");
//    printf("102\n");
//    goto label;
int i = 0;
label:
printf("%d\n", i);
i++;
if (i < 100) {
goto label;
}

return 0;
}

4.for 循环
#include <stdio.h>

int main() {

//for循环
for (int i = 0; i < 100; ++i) {
printf("Number :%d\n", i);
}

//for循环跳出
for (int i = 0; i < 100; ++i) {
printf("Number :%d\n", i);
if (i > 50) {
break;
}
}

//for循环嵌套
for (int i = 0; i < 100; ++i) {
printf("Number :%d\n", i);
for (int j = 0; j < 10; ++j) {
printf("%d", j);
}
printf("\n");
}

//for循环 乘法口诀
for (int i = 1; i <= 9; ++i) {
for (int j = 1; j <= i; ++j) {
printf("%d*%d=%d\t", i, j, i * j);
}
printf("\n");
}

//break 跳出循环 continue 跳出本次循环
for (int i = 0; i < 100; ++i) {
printf("Item :%d\n", i);
if (i == 50){
// break;
continue;
}
printf("Number :%d\n", i);
}

return 0;
}
5.while 循环和 do-while 循环
#include <stdio.h>

int main() {

int i = 0;
//while循环
while (i < 100) {
printf("%d\n", i);
i++;
}

//奇数
while (i < 100) {
if (i % 2) { //结果 1是真 0是假
printf("%d\n", i);
i++;
}
}

//do-while 先执行 再判断
do {
printf("%d\n", i);
i++;
} while (i < 100);

//比较
while (i < 0) {
printf("while:%d\n", i);
i++;
}
do {
printf("do-while:%d\n", i);
i++;
} while (i < 0);

return 0;
}