Chapter2 专注于显示

//2-1输出\a和\n
#include<stdio.h>
int main(){
    printf("你好。\n初次见面。\n");
    printf("\a警告。\n\n");
    printf("\a\a这次是第二次警告。\n");
    return 0;
}

//2-2\b使用实例，每个1秒消去一个字符
#include<time.h>
#include<stdio.h>

int sleep(unsigned long x){        //等待x毫秒
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}

int main(){
    int i;
    
    printf("ABCDEFG");
    for(i = 0; i < 7; i++){
        sleep(1000);
        printf("\b \b");
        fflush(stdout);        //清空缓存
    }
    return 0;
}

//2-3\r回车符的使用示例：重写行
#include<time.h>
#include<stdio.h>

int sleep(unsigned long x){        //等待x毫秒
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}

int main(){
    printf("My name is BohYoh.");
    fflush(stdout);
    
    sleep(2000);
    printf("\rHow do you do?    ");
    fflush(stdout);
    
    sleep(2000);
    printf("\rThanks.            ");
    
    return 0;
}

//2-4\'\"使用示例
#include<stdio.h>
int main(){
    printf("关于字符串常量和字符常量。\n");
    
    printf("双引号");
    putchar('"');
    printf("用双引号括起来的\"ABC\"是字符串常量。\n");
    
    printf("单引号");
    putchar('\'');
    printf("用双引号括起来的'A'是字符常量。\n");
    
    return 0;
}

//2-5倒计时后显示程序运行的时间
#include<time.h>
#include<stdio.h>

int sleep(unsigned long x){
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}
int main(){
    int i;
    clock_t c;
    
    for(i = 10; i > 0; i--){
        printf("\r%2d", i);
        fflush(stdout);
        sleep(1000);
    }
    printf("\r\aFIRE!!\n");
    c = clock();
    printf("程序开始后经过了%.1f秒。\n", (double)c / CLOCKS_PER_SEC);
    return 0;
}

//2-6心算训练，连加三个整数的时间
#include<time.h>
#include<stdio.h>
#include<stdlib.h>

int main(){
    int a, b, c;
    int x;
    clock_t start, end;
    double req_time;
    
    srand(time(NULL));
    a = 100 + rand() % 900;
    b = 100 + rand() % 900;
    c = 100 + rand() % 900;
    printf("%d + %d + %d等于多少：", a, b, c);
    
    start = clock();
    while(1){
        scanf("%d", &x);
        if(x == a + b + c)
            break;
        printf("\a回答错误！！\n请重新输入：");
    }
    end = clock();
    
    req_time = (double)(end - start) / CLOCKS_PER_SEC;
    printf("用时%.1f秒。\n", req_time);
    if(req_time > 30.0)
        printf("花太长时间了吧。\n");
    else if (req_time > 17.0)
        printf("还行吧。\n");
    else
        printf("真快啊。\n");
    return 0;
}

//2-7即那个sleep函数

//2-8逐个显示字符，显示完后再逐个从后往前消除，反复执行此操作
#include<time.h>
#include<stdio.h>
#include<string.h>

int sleep(unsigned long x){
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}

int main(){
    int i;
    char name[] = "BohYoh Shibata";
    int name_len = strlen(name);
    
    while(1){
        for(i = 0; i < name_len; i++){        //从头开始逐个显示字符
            putchar(name[i]);
            fflush(stdout);
            sleep(500);
        }
        for(i = 0; i < name_len; i++){        //从未开始逐个消去字符
            printf("\b \b");
            fflush(stdout);
            sleep(500);
        }
    }
    return 0;
}

//2-9从右往左滚动字符
#include<time.h>
#include<stdio.h>
#include<string.h>

int sleep(unsigned long x){
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}

int main(){
    int i;
    int cnt = 0;    //第几个字符显示在最前面
    char name[] = "BohYoh ";
    int name_len = strlen(name);
    
    while(1){
        putchar('\r');
        for(i = 0; i < name_len; i++){
            if(cnt + i < name_len)
                putchar(name[cnt + i]);
            else 
                putchar(name[cnt + i - name_len]);
        }
        fflush(stdout);
        sleep(500);
        
        if(cnt < name_len - 1)
            cnt++;
        else
            cnt = 0;
    }
    return 0;
}

//2-10从左往右滚动字符
#include<time.h>
#include<stdio.h>
#include<string.h>

int sleep(unsigned long x){
    clock_t c1 = clock(), c2;
    do{
        if((c2 = clock()) == (clock_t) - 1)
            return 0;
    } while(1000.0 * (c2 - c1) / CLOCKS_PER_SEC < x);
    return 1;
}

int main(){
    int i;
    int cnt = 0;    //第几个字符显示在最前面
    char name[] = "BohYoh ";
    int name_len = strlen(name);
    
    while(1){
        putchar('\r');
        for(i = 0; i < name_len; i++){
            if(cnt + i < name_len)
                putchar(name[cnt + i]);
            else 
                putchar(name[cnt + i - name_len]);
        }
        fflush(stdout);
        sleep(500);
        
        if(cnt > 0)        //与2-9只有这个if不同
            cnt--;
        else
            cnt = name_len - 1;
    }
    return 0;
}

//2-11把数字字符每次偏移1位显示
#include<stdio.h>
int main(){
    int i, j;
    int x;
    
    printf("要显示多少行：");
    scanf("%d", &x);
    
    for(i = 1; i <= x; i++){
        for(j = 1; j < i; j++)
            putchar(' ');        //显示i-1个空白字符
        printf("%d\n", i % 10);
    }
    return 0;
}

//2-12把数字字符每次偏移1位显示 第二版
#include<stdio.h>
int main(){
    int i;
    int x;
    printf("要显示多少行：");
    scanf("%d", &x);
    
    for(i = 1; i <= x; i++)
        printf("%*d\n", i, i % 10);        //第二个参数放入*
    return 0;
}

 

//2-13同时训练扩大水平方向视野的心算训练
#include<time.h>
#include<stdio.h>
#include<stdlib.h>

int main(){
    int stage;
    int a, b, c;
    int x; 
    int n;//空白的宽度
    clock_t start, end;
    
    srand(time(NULL));
    printf("扩大视野心算训练开始！！\n");
    start = clock();
    
    for(stage = 0; stage < 10; stage++){
        a = 10 +rand() % 90;
        b = 10 +rand() % 90;
        c = 10 +rand() % 90;
        n = rand() % 17;
        printf("%d%*s+%*s%d%*s+%*s%d: ", a, n, "", n, "", b, n, "", n, "", c);
        do{
            scanf("%d", &x);
            if(x == a + b + c)
                break;
            printf("\a回答错误。请重新输入： ");
        } while(1);
    }
    end = clock();
    printf("用时%.1f秒。\n", (double)(end - start) / CLOCKS_PER_SEC);
    return 0;
}