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;
}