《C语言程序设计（第二版新版）》第三章习题解答（部分）

3-2

#include <stdio.h>#define MAXLINE 100void escape(char s[], char t[]);void dis_escape(char s[], char t[]);int getline(char line[], int);int main(){char s[MAXLINE], t[MAXLINE];while (1){getline(s, MAXLINE);getline(t, MAXLINE);escape(s, t);printf("After:\ns:%s\n", s);escape(t, s);printf("After:\nt:%s\n", t);}return 0;}int getline(char line[], int lim){int i, c;i = 0;printf("input:\n");while (i < lim - 1 && (c = getchar()) != '\n' && c != EOF){line[i] = c;i++;}if (c == '\n'){line[i] = c;i++;}line[i] = '\0';return i;}void escape(char s[], char t[]){int sn, tn;sn = 0;tn = 0;while (s[sn] != '\n')sn++;while (t[tn] != '\0'){switch (t[tn]){case '\n':s[sn++] = '\\';s[sn++] = 'n';break;case '\t':s[sn++] = '\\';s[sn++] = 't';break;default:s[sn++] = t[tn];break;}tn++;//s[sn++] = t[tn++];}s[sn] = '\0';}void dis_escape(char s[], char t[]){int sn, tn;sn = 0;tn = 0;while (s[sn] != '\n')sn++;while (t[tn] != '\0'){if (t[tn] == '\\'){tn++;switch (t[tn]){case 'n':s[sn++] = '\n';break;case 't':s[sn++] = '\t';break;default:s[sn++] = '\\';s[sn++] = t[tn];break;}}elses[sn++] = t[tn];tn++;}s[sn] = '\0';}

3-3

#include <stdio.h>#define MAXLINE 100void espand(char s1[], char s2[]);int getline(char line[], int);int main(){char s1[MAXLINE], s2[MAXLINE];while (1){getline(s1, MAXLINE);espand(s1, s2);printf("t:\n%s\n", s2);}return 0;}int getline(char line[], int lim){int i, c;i = 0;printf("input:\n");while (i < lim - 1 && (c = getchar()) != '\n' && c != EOF){line[i] = c;i++;}if (c == '\n'){line[i] = c;i++;}line[i] = '\0';return i;}void espand(char s1[], char s2[]){char before, now,i;int n1, n2, status, before_status, flag,end;n1 = 0;n2 = 0;before = '\0';status = 0;before_status = 0;flag = 0;end = 0;while (s1[n1] != '\0'){now = s1[n1];if (now >= '0' && now <= '9')status = 1;else if (now >= 'a' && now <= 'z')status = 2;else if (now >= 'A' && now <= 'Z')status = 3;elsestatus = 0;if (flag){if (status == before_status && before < now){for (i = before; i < now; i++)s2[n2++] = i;}else{s2[n2++] = before;s2[n2++] = '-';}end = 1;s2[n2++] = now;}else if (now == '-' && before == '\0'){s2[n2++] = '-';end = 1;}else if (now != '-' && before != '\0'){s2[n2++] = before;}if (end){before = 0;flag = 0;end = 0;}else{if (now != '-'){flag = 0;before = now;before_status = status;}elseflag = 1;}n1++;}s2[n2] = '\0';}

3-4

#include <stdio.h>#include <string.h>#define MAXLINE 100void itoa(char n, char s[]);void reverse(char s[]);int main(){int n;char s[MAXLINE];while (1){printf("input:\n");scanf("%d", &n);itoa(n, s);printf("s:\n%s\n", s);}return 0;}void itoa(char n, char s[]){char i, sign;printf("n:\n%o\n", n);//'~'是取反if ((sign = n) < 0)n = -n;//'-'是求补码i = 0;if (n != -128){do{s[i++] = n % 10 + '0';} while ((n /= 10) > 0);if (sign < 0)s[i++] = '-';}else{n++;n = -n;do{s[i++] = n % 10 + '0';} while ((n /= 10) > 0);s[0]++;if (sign < 0)s[i++] = '-';}s[i] = '\0';reverse(s);}void reverse(char s[]){int c, i, j;for (i = 0, j = strlen(s) - 1; i < j; i++, j--){c = s[i];s[i] = s[j];s[j] = c;}}

3-5

#include <stdio.h>#include <string.h>#define MAXLINE 100void itob(int n, char s[], int b);void reverse(char s[]);int main(){int n, b;char s[MAXLINE];while (1){printf("input n:\n");scanf("%d", &n);printf("input b:\n");scanf("%d", &b);itob(n, s, b);printf("s:\n%s\n", s);}return 0;}void itob(int n, char s[],int b){int i, sign;if ((sign = n) < 0)n = -n;//'-'是求补码i = 0;if(b > 10){do{s[i] = n % b + '0';if (s[i] > '9'){s[i] = s[i] - '9' - 1 + 'A';}i++;} while ((n /= b) > 0);}else{do{s[i++] = n % b + '0';} while ((n /= b) > 0);}if (sign < 0)s[i++] = '-';s[i] = '\0';reverse(s);}void reverse(char s[]){int c, i, j;for (i = 0, j = strlen(s) - 1; i < j; i++, j--){c = s[i];s[i] = s[j];s[j] = c;}}

3-6

#include <stdio.h>#include <string.h>#define MAXLINE 100void itoa(char n, char s[],int width);void reverse(char s[]);int main(){int n,width;char s[MAXLINE];while (1){printf("input n:\n");scanf("%d", &n);printf("input width:\n");scanf("%d", &width);itoa(n, s, width);printf("s:\n%s\n", s);}return 0;}void itoa(char n, char s[], int width){char i, sign;printf("n:\n%o\n", n);//'~'是取反if ((sign = n) < 0)n = -n;//'-'是求补码i = 0;if (n != -128){do{s[i++] = n % 10 + '0';} while ((n /= 10) > 0);if (sign < 0)s[i++] = '-';}else{n++;n = -n;do{s[i++] = n % 10 + '0';} while ((n /= 10) > 0);s[0]++;if (sign < 0)s[i++] = '-';}for (; i < width; i++)s[i] = ' ';s[i] = '\0';reverse(s);}void reverse(char s[]){int c, i, j;for (i = 0, j = strlen(s) - 1; i < j; i++, j--){c = s[i];s[i] = s[j];s[j] = c;}}