C Primer Plus 第6版 编程练习答案（第八章）
— C Primer Plus, 编程 — 5 min read
8.1.c
#include <stdio.h>int main(void) { int ch; int ct = 0;
while ((ch = getchar()) != EOF) ++ct; printf("%d characters read\n", ct); return 0;}8.2.c
#include <stdio.h>int main(void) { int ch, ct; ct = 0; while((ch = getchar()) != EOF) { if(ct == 10) { printf("\n"); ct = 0; ct++; } if(ch == '\n') printf("\\n "); else if(ch == '\t') printf("\\t "); else if(ch < ' ') printf("^%c ", ch + 64); else printf("%c = %d ", ch, ch); ct++; } return 0;}8.3.c
#include <stdio.h>#include <ctype.h>int main(void) { int ch; unsigned long uct = 0; unsigned long lct = 0; unsigned long oct = 0;
while ((ch = getchar()) != EOF) if (isupper(ch)) uct++; else if (islower(ch)) lct++; else oct++; printf("%lu uppercase characters read\n", uct); printf("%lu lowercase characters read\n", lct); printf("%lu other characters read\n", oct); return 0;}8.4.c
#include <stdio.h>#include <ctype.h>#include <stdbool.h>int main(void) { int ch; int ct_letter = 0; int ct_word = 0; float num; bool isword = false; while((ch = getchar()) != EOF) { if(ispunct(ch)) continue; if(isalpha(ch)) ++ct_letter; if(!isspace(ch) && !isword) { isword = true; ++ct_word; } if(isspace(ch) && isword) isword = false; } num = (float)ct_letter / ct_word; printf("Total words: %d.\n", ct_word); printf("Total letters: %d.\n", ct_letter); printf("Average letters of words: %f.\n", num); return 0;}8.5.c
#include <stdio.h>#include <ctype.h>int main(void) { int high = 100; int low = 1; int guess = (high + low) / 2; char response; printf("Pick an integer from 1 to 100. I will try to guess "); printf("it.\nRespond with a y if my guess is right, with"); printf("\na h if it is high, and with an l if it is low.\n"); printf("Uh...is your number %d?\n", guess); while ((response = getchar()) != 'y') { if (response == '\n') continue; if (response != 'h' && response != 'l') { printf("I don't understand that response. Please enter h for\n"); printf("high, l for low, or y for correct.\n"); continue; } if (response == 'h') high = guess - 1; else if (response == 'l') low = guess + 1; guess = (high + low) / 2; printf("Well, then, is it %d?\n", guess); } printf("I knew I could do it!\n"); return 0;}8.6.c
#include <stdio.h>#include <ctype.h>#define STOP '#'int get_first(void);int main(void) { int ch;
while ((ch = get_first()) != STOP) { printf("%c\n", ch); } return 0;}
int get_first(void) { int ch;
do { ch = getchar(); } while (isspace(ch)); while (getchar() != '\n') continue; return ch;}8.7.c
#include <stdio.h>#include <ctype.h>#define BASEPAY1 8.75 // $8.75 per hour#define BASEPAY2 9.33 // $9.33 per hour#define BASEPAY3 10.00 // $10.00 per hour#define BASEPAY4 11.20 // $11.20 per hour#define BASEHRS 40 // hours at basepay#define OVERTIME 1.5 // 1.5 time#define AMT1 300 // 1st rate tier#define AMT2 150 // 2st rate tier#define RATE1 0.15 // rate for 1st tier#define RATE2 0.20 // rate for 2nd tier#define RATE3 0.25 // rate for 3rd tierint getfirst(void);void menu(void);int main(void) { double hours; double gross; double net; double taxes; double pay; char response;
menu(); while ((response = getfirst()) != 'q') { if (response == '\n') continue; response = tolower(response); switch (response) { case 'a': pay = BASEPAY1; break; case 'b': pay = BASEPAY2; break; case 'c': pay = BASEPAY3; break; case 'd': pay = BASEPAY4; break; default : printf("Please enter a, b, c, d, or q.\n"); menu(); continue; } printf("Enter the number of hours worked this week: "); scanf("%lf", &hours); if (hours <= BASEHRS) gross = hours * pay; else gross = BASEHRS * pay + (hours - BASEHRS) * pay * OVERTIME; if (gross <= AMT1) taxes = gross * RATE1; else if (gross <= AMT1 + AMT2) taxes = AMT1 * RATE1 + (gross - AMT1) * RATE2; else taxes = AMT1 * RATE1 + AMT2 * RATE2 + (gross - AMT1 - AMT2) * RATE3; net = gross - taxes; printf("gross: $%.2f; taxes: $%.2f; net: $%.2f\n", gross, taxes, net); menu(); } printf("Done.\n"); return 0;}void menu(void) { printf("********************************************************" "*********\n"); printf("Enter the letter corresponding to the desired pay rate" " or action:\n"); printf("a) $%4.2f/hr b) $%4.2f/hr\n", BASEPAY1, BASEPAY2); printf("c) $%5.2f/hr d) $%5.2f/hr\n", BASEPAY3, BASEPAY4); printf("q) quit\n"); printf("********************************************************" "*********\n");}int getfirst(void) { int ch; ch = getchar(); while (isspace(ch)) ch = getchar(); while (getchar() != '\n') continue; return ch;}8.8.c
#include <stdio.h>int get_choice(void);float get_input(void);int main(void) { int ch; float n_first, n_second, value; while((ch = get_choice()) != 'q') { printf("Enter first number: "); n_first = get_input(); printf("Enter second number: "); n_second = get_input(); switch(ch) { case 'a': value = n_first + n_second; printf("%g + %g = %g\n", n_first, n_second, value); break; case 's': value = n_first - n_second; printf("%g - %g = %g\n", n_first, n_second, value); break; case 'm': value = n_first * n_second; printf("%g * %g = %g\n", n_first, n_second, value); break; case 'd': if(n_second == 0) { printf("Enter a number other than 0: "); n_second = get_input(); } value = n_first / n_second; printf("%g / %g = %g\n", n_first, n_second, value); break; } } printf("Bye.\n"); return 0;}int get_choice(void) { int 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 = getchar(); while(ch != 'a' && ch != 'b' && ch != 'c' && ch != 'd' && ch != 'q') { printf("Please enter a,b,c,d or q\n"); ch = getchar(); } return ch;}float get_input(void) { float input; int ch; while(scanf("%f", &input) != 1) { while((ch = getchar()) != '\n') putchar(ch); printf(" is not an number.\n"); printf("Please enter a number, such as 2.5, -1.78E8, or 3: "); } while(getchar() != '\n') continue; return input;}