C Primer Plus 第8章 字符输入/输出和验证输入 编程练习

1.
#include <stdio.h>
int main(){
char ch;
int ct = 0;
while ((ch=getchar()) != EOF)
ct++;
printf("%d characters read.", ct);
return 0;
}

2.
#include <stdio.h>
int main(){
char ch;
int ct = 0;
while ((ch = getchar()) != EOF)
{
if (ch >= 32){
putchar(ch);
printf("/%d  ",ch);
ct++;
}
else if (ch == '\n'){
printf("\\n");
putchar(ch);
ct = 0;  //因为要换新的一行了所以ct清0
}
else if (ch == '\t'){

printf("\\t");
ct++;
}
else  //打印控制字符
{
putchar('^');
putchar(ch + 64);
printf("/%d  ", ch);
}
if (ct == 10){
printf("\n");
ct = 0;
}
}
return 0;
}

3.
#include <stdio.h>
#include <ctype.h>
int main(){
char ch;
int a,b,c;
a = b = c = 0;
while ((ch = getchar()) != '#')
{
if (isupper(ch))
a++;
else if (islower(ch))
b++;
else c++;
}
printf("capital:%d lower case:%d other:%d", a, b, c);
return 0;
}

4.
#include <stdio.h>
#include <ctype.h> //用来区分字母和字母的大小写
#include <stdbool.h>
int main(){
char ch;
bool inword = false;
int n_chars = 0;
int n_words = 0;
int value;
while ((ch = getchar()) != '#')
{
if (isalpha(ch))
n_chars++;
if (!isspace(ch) && !inword)
{
inword = true; //开始一个新的单词
n_words++; //单词加1
}
if (isspace(ch) && inword)
inword = false; //单词结束
}
value = n_chars / n_words ;
printf("chars : %d\n", n_chars);
printf("words : %d\n", n_words);
printf("average value : %d", value);
return 0;
}

5.
#include <stdio.h>
//如果50太大，则50变为最大值。反之则为最小值。
int main(){
char ch;
int guess = 50, MAX = 100, MIN = 0;
printf("Uh...is your number is %d\n",guess);
while ((ch = getchar()) != 'y')
{
if (ch == 'b') {
MAX = guess;
guess = (guess + MIN) / 2;
printf("Well, then, is it %d\n",guess);
}
else if (ch == 'l') {
MIN = guess;
guess = (guess + MAX) / 2;
printf("Well, then, is it %d\n",guess);
}
else printf("Sorry, I understand only big , less , yes.\n");
while ((ch = getchar()) != '\n')
continue;
}
printf("I konw i could do it");
return 0;
}

6.
//重要！！
char get_first(void){
char ch;
while((ch = getchar()) == '\n')
continue;
while (getchar() != '\n')
continue;
return ch;
}

7.
#include <stdio.h>
char get_choice(void);
char get_first(void);
#define WORK_OVERTIME 40
#define RATE1 0.15
#define RATE2 0.20
#define RATE3 0.25
#define BREAK1 300.0
#define BREAK2 450.0
#define BASE1 (BREAK1 * RATE1)
#define BASE2 (BASE1 + ((BREAK2 - BREAK1) * RATE2))
int main(void) {
int hr;
char choice;
double wage,income,tax,wage2;
printf("------------------------------------------------------------------------\n");
printf("Enter the number number corresponding to the desired pay rate or action:\n");
printf("a) $8.15/hr                       b) $9.33/hr\n");
printf("c) $10.00/hr                      d) $11.20/hr\n");
printf("q) quit\n");
printf("------------------------------------------------------------------------\n");
printf("Please enter your choise:");
while (choice = get_choice() ){
if (choice == 'q')
break;
switch (choice){
case 'a': wage2 = 8.75;
break;
case 'b': wage2 = 9.33;
break;
case 'c': wage2 = 10.00;
break;
case 'd': wage2 = 11.20;
break;
}
printf("Please enter the hours:");
scanf("%d",&hr);
if (hr <= WORK_OVERTIME)
wage = hr * wage2;
else wage = WORK_OVERTIME * wage2 +((hr - WORK_OVERTIME) * wage2 * 1.5);
if (wage <= BREAK1){
tax = wage * RATE1;
}
else if (wage > 300 && wage <= 450 ){
tax = BASE1 + (wage - BREAK1) * RATE2;
}
else tax = BASE2 + (wage - BREAK2) * RATE3;
income = wage - tax;
printf("The wage: %.2f income:%.2lf tax:%.2lf\n", wage, income, tax);
printf("------------------------------------------------------------------------\n");
printf("Enter the number number corresponding to the desired pay rate or action:\n");
printf("1) $8.15/hr                       2) $9.33/hr\n");
printf("3) $10.00/hr                      4) $11.20/hr\n");
printf("5) quit\n");
printf("------------------------------------------------------------------------\n");
printf("Please enter your choise:");
}
return 0;
}
//get_choice 输入正确的符号
char get_choice(void){
char ch;
ch = get_first();
while (ch != 'q' && (ch < 'a' || ch > 'd')){
printf("Please enter the : a b c d q\n");
printf("Please enter your choise:");
ch = get_first();
}
return  ch;
}
//get_first 读取第一个符号 扔掉其他符号
char get_first(void){
int ch;
ch = getchar();
while (getchar() != '\n')
continue;
return ch;
}

8.
#include <stdio.h>

char get_choice(void);
char get_first(void);
double get_number(void);

int main(void){
char choice;
double num1,num2,result;

while ((choice = get_choice()) != 'q'){
printf("Enter the first number:");
num1 = get_number();
printf("Enter the second number:");
num2 = get_number();
if (choice == 'a') {
result = num1 + num2;
printf("%.1lf + %.1lf = %.1lf\n", num1, num2, result);
}
if (choice == 's') {
result = num1 - num2;
printf("%.1f - %.1f = %.1f\n", num1, num2, result);
}
if (choice == 'm') {
result = num1 * num2;
printf("%.1f * %.1f = %.1f\n", num1, num2, result);
}
if (choice == 'd') {
if (num2 == 0) {
printf("Enter a number other than 0: ");
num2 = get_number();
result = num1 / num2;
printf("%.1f / %.1f = %.1f\n",  num1, num2, result);
} else
printf("%.1f / %.1f = %.1f\n", num1, num2, result);
}
}

return 0;
}

char get_choice(void){
char ch;
printf("Enter the operation of your choice:\n");
printf("a. add            s. subtract\n");
printf("m. multiply       d. divide\n");
printf("q. quit\n");
ch = get_first();
while ((ch != 'a') && (ch != 's') && (ch != 'm') && (ch != 'd') && (ch != 'q')){
printf("Please choice such as a s m d q:");
ch = get_first();
}
return ch;
}

char get_first(void){
char ch;
while((ch = getchar()) == '\n')//ch = getchar();之前用的的是这个，结果总是把回车给ch
continue;    //还总是检查不出来问题，终于找出来问题在哪里了。！！
while (getchar() != '\n')
continue;
return ch;
}

double get_number(void){
double num;
char ch;
while (scanf("%lf", &num) != 1){
while ((ch = getchar()) != '\n')
putchar(ch); //处理错误的输入。
printf("is not an number.\n");
printf("Please enter a number , such as 2.5, -1.78E8, or 3:");
}
return num;
}