c程序设计语言笔记1

打印最长输入行的程序：

#include <stdio.h>#define MAXLINE 1000/*允许的输入行的最大长度*/int getline(char line[], int maxline);void copy(char to[], char from[]);/* 打印最长的输入行 */main(){int len;/*当前行长度*/int max;/*目前为止发现的最长行的长度*/char line[MAXLINE];/*当前的输入行*/char longest[MAXLINE];/*用于保存最长的行*/max = 0;while((len = getline(line,MAXLINE)) > 0)if (len > max){max = len;copy(longest,line);}if (max > 0)printf("%s",longest);return 0;}/*getline函数：将一行读入到s并返回其长度*/int getline(char s[], int lim){int c, i;for (i = 0;i <= lim-1 && (c=getchar())!=EOF && c!='\n';++i)s[i] = c;if (c = '\n'){s[i] = c;++i;}s[i] = '\0';return i;}/* copy函数：将from复制到to；这里假定to足够大*/void copy(char to[], char from[]){int i;i = 0;while((to[i] = from[i] != '\0'))++i;}

练习1-9 编写一个将输入复制到输出的程序，并将其中连续的多个空格用一个空格代替。

#include <stdio.h>/* ex1-9,编写一个将输入复制到输出的程序，并将其中的连续多个空格用一个空格代替*/#define NONBLACK 'a'/*main(){int i = 0,c,c_prior;  //加入i使得一开始连续输入空格时不输出c_prior = NONBLACK;  //初始化，防止一开始输入空格时出现错误while((c = getchar()) != EOF){if (c != ' '){putchar(c);i++;}else if(c_prior != ' '&& i > 0)putchar(c);c_prior = c;}getch();}    *///or版本main(){int  c,c_prior;c_prior = NONBLACK;while((c = getchar()) != EOF){if(c != ' ' || c_prior != ' ')putchar(c);c_prior = c;}getch();}

练习1-12 

#include <stdio.h>// ex 1-12  以每行一个单词的形式打印其输入#define IN 1 // inside a word #define OUT 0 // outside a wordmain(){int c,state;state = OUT;while((c = getchar()) != EOF){if(c == ' ' || c== '\n' || c == '\t' ){if(state == IN){putchar('\n'); //finish a wordstate = OUT;}else if(state == OUT){state = IN;putchar(c);}elseputchar(c);}}}

练习1-13 

水平直方图：

#include <stdio.h>#include <stdlib.h>//ex 1-13//print horizontal histogram#define MAXHIST 15 /* max length of histogram*/#define MAXWORD 11 /* max length of a word*/#define IN 1/* inside a word*/#define OUT 0   /* outside a word   */main(){int c,i,nc,state;int len;  /*  length pf each word */int maxvalue;   /* maxunum value for wl[]   */int ovflow;/* number of overflow word */int wl[MAXWORD];/*word length counters*/state = OUT;nc = 0;/*number of chars in a word  */ovflow = 0;for (i = 0;i < MAXWORD; ++i)wl[i] = 0;while((c = getchar()) != '\n'){if (c == ' ' || c == '\t'){state = OUT;if (nc > 0)if (nc < MAXWORD)++wl[nc];else++ovflow;nc = 0;}else if (state == OUT){state = IN;nc = 1;    /* beginning of a new word*/}elsenc++;    /*inside  a word   */}maxvalue = 0;for (i = 1;i < MAXWORD; i++)if (wl[i] > maxvalue)maxvalue = wl[i];for (i = 1;i < MAXWORD; i++){printf("%5d - %5d : ", i, wl[i]);/*if(wl[i] > 0){if ((len = wl[i] * MAXHIST / maxvalue) <= 0)len = 1;}else len = 0;  */len = wl [i];while (len > 0){putchar('*');--len;}putchar('\n');}if (ovflow > 0)printf("There are %d words >= %d\n", ovflow , MAXWORD);system("pause");}

垂直直方图：

#include <stdio.h>#include <stdlib.h>//ex 1-13//print horizontal histogram#define MAXHIST 15 /* max length of histogram*/#define MAXWORD 11 /* max length of a word*/#define IN 1/* inside a word*/#define OUT 0   /* outside a word   */main(){int c,i,j,nc,state;int len;  /*  length pf each word */int maxvalue;   /* maxunum value for wl[]   */int ovflow;/* number of overflow word */int wl[MAXWORD];/*word length counters*/state = OUT;nc = 0;/*number of chars in a word  */ovflow = 0;for (i = 0;i < MAXWORD; ++i)wl[i] = 0;while((c = getchar()) != '\n'){if (c == ' ' || c == '\t'){state = OUT;if (nc > 0)if (nc < MAXWORD)++wl[nc];else++ovflow;nc = 0;}else if (state == OUT){state = IN;nc = 1;    /* beginning of a new word*/}elsenc++;    /*inside  a word   */}maxvalue = 0;for (i = 1;i < MAXWORD; i++)if (wl[i] > maxvalue)maxvalue = wl[i];for (i = MAXHIST;i > 0; --i){for (j = 1;j < MAXWORD; ++j)if (wl[j] >= i)printf("   * ");elseprintf("      ");putchar('\n');}for (i = 1;i < MAXWORD; ++i)printf("%4d ",i);putchar('\n');for (i = 1; i < MAXWORD; ++i)printf("%4d ",wl[i]);putchar('\n');if (ovflow > 0)printf("There are %d words >= %d\n", ovflow , MAXWORD);system("pause");}

练习1-20detab函数

#include <stdio.h>#include <stdlib.h>// ex 1-20 编写程序detab#define TABINC 8   /* tab increment size  *//* replace tabs with the proper number of blanks   */main(){int c,pos,nb;nb = 0;/*number of blanks necessary  */pos = 1;/*position of character in line  */while((c = getchar()) != EOF){if (c == '\t'){nb = TABINC - (pos - 1) % TABINC;while(nb > 0){  putchar(' ');++pos;--nb;}}else if (c == '\n'){pos = 1;putchar(c);}else{++pos;putchar(c);}}system("pause");}