c primer plus第四章习题

background

也没有啥新的东西，这一章都是格式化字符串

1

#include <stdio.h>

int main(void) {
    char fname[50]; // 声明字符数组来存储名字
    char lname[50]; // 声明字符数组来存储姓氏
    
    printf("请输入名和姓：");
    scanf("%s %s", fname, lname); // 使用 %s 格式接收字符串输入
    printf("%s, %s", fname, lname); 
    return 0;
}

/*使用char[]数组来接收变量*/

2

#include<stdio.h>

int main(void){
    char name[10];
    int len;
    printf("请输入姓名：");
    scanf("%s",&name);
    len=strlen(name);
    printf("\"%s\"\n",name);
    printf("\"%20s\"\n",name);
    printf("\"%-20s\"\n",name);
    printf("\"%*s\"",len+3,name);
} 

/*%s还可以控制位置，*还可以占位*/

3

//4_3 读取一个浮点数，小数点计数法打印和指数计数法打印

#include <stdio.h>

int main(void){
    float input;
    
    printf("请输入一个浮点数：");
    scanf("%f", &input);
    printf("%.1f,  %.1e\n", input, input);
    printf("%f,  %e", input, input);
    return 0;
} 
/*数据类型那点事  懒得看*/

4

#include <stdio.h>

int main(void){
    float cm;
    char name[50];
    
    printf("请输入你的名字：");
    scanf("%s", &name);
    printf("\n请输入你的身高：");
    scanf("%f", &cm);

    printf("你好%s,你有%.2fM。",name,cm/100);
    return 0;
} 

/*格式化字符串问题*/

5

#include<stdio.h>
#define BIT_TO_BYTE 8     //每字节包含的位数

int main(void)
{
    float m_speed;
    float b_speed;
    float file_size;
    printf("Enter the download speed in megabits per second(Mbs): ");
    scanf("%f",&b_speed);
    m_speed = b_speed/BIT_TO_BYTE;
    printf("Enter the size of a file in megabytes (MB):");
    scanf("%f",&file_size);
    printf("Download speed(MBs): %.2f\n",m_speed);
    printf("File size(MB): %.2f\n",file_size);
    printf("Download time(s): %.2f\n",file_size/m_speed);
    
    return 0;
}

/*也是转来转去*/

6

#include<stdio.h>
#include<string.h>
int main(void)
{
    char first_name[20];
    char last_name[20];
    printf("Enter your first name and last name: ");
    scanf("%s",first_name);
    scanf("%s",last_name);
    printf("%s %s\n",first_name,last_name);
    printf("%*d %*d\n",strlen(first_name),strlen(first_name),strlen(last_name),strlen(last_name));
    printf("%s %s\n",first_name,last_name);
    printf("%-*d %-*d\n",strlen(first_name),strlen(first_name),strlen(last_name),strlen(last_name));
    return 0;
}

/*花拳绣腿*/

7

#include<stdio.h>
#include<float.h>  //DBL_DIG, FLT_DIG

int main(void)
{
    double num1 = 1.0/3.0;
    float num2 = 1.0/3.0;
    printf("double: %.4f %.12f %.16f\n",num1,num1,num1);
    printf("float:  %.4f %.12f %.16f\n",num2,num2,num2);
    printf("DBL_DIG: %d\nFLT_DIG: %d",DBL_DIG,FLT_DIG);

    return 0;
}

/*花拳绣腿*/

8

#include<stdio.h>

int main(void)
{
    const float gallon_to_liter = 3.785;     //每加仑相等的公升数
    const float mile_to_kilometer = 1.609;   //每英里相等的公里数
    float traveled_miles;
    float traveled_kilometers;
    float gasoline_gallons;
    float gasoline_liters;

    printf("Enter the number of miles traveled: ");
    scanf("%f",&traveled_miles);
    printf("Enter the number of gallons of gasoline consumed: ");
    scanf("%f",&gasoline_gallons);
    printf("The miles-per-gallon Value: %.1f\n",traveled_miles/gasoline_gallons);

    traveled_kilometers = traveled_miles*mile_to_kilometer;      //英里转公里
    gasoline_liters = gasoline_gallons*gallon_to_liter;          //加仑转公升

    printf("The liter-per-100-km value: %.1f\n",gasoline_liters/traveled_kilometers*100);

    return 0;
}

/*使用const来定义常量
就是些单位的换算，编程本身的知识点前面已经练习过了*/