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 word

main()
{
	int c,state;
	state = OUT;
	while((c = getchar()) != EOF){
		if(c == ' ' || c== '\n' || c == '\t' ){
			if(state == IN){
				putchar('\n'); //finish a word
				state = OUT;
			}
			else if(state == OUT){
				state = IN;
				putchar(c);
			}
			else
				putchar(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	*/
		}else
			nc++;    /*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	*/
		}else
			nc++;    /*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("   * ");
			else
				printf("      ");
		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");
}