unix下more命令的简单实现：

#include <stdio.h>

#define PAGELEN 24

#define LINELEN 512

int do_more(FILE * file);

int see_more(FILE * file);

int main(int argc,char * argv[])

{

	FILE * fp;

	if(argc == 1)

		do_more(stdin);

	else

	{

		int argv_index = 1;

		while(argc > 1)

		{

			if((fp = fopen(argv[argv_index],"r")) == NULL)

				exit(1);

			do_more(fp);

			fclose(fp);

			argv_index++;

			argc--;

		}

	}

	return 0;

}

int do_more(FILE * fp)

{

	char buffer[LINELEN];

	int number_of_lines = 0;

	int reply;

	FILE * ftty;

	ftty = fopen("/dev/tty","r");

	if(ftty == NULL)

		exit(1);

	while(fgets(buffer,LINELEN,fp))

	{

		if(number_of_lines == PAGELEN)

		{

			fputs(buffer,stdout);

			reply = see_more(ftty);

			if(reply == 0)

				break;

			if(reply == 1)

				number_of_lines = 0;

			//if(reply == 2)

			//	number_of_lines--;

		}

		else

		{

			number_of_lines++;

			fputs(buffer,stdout);

		}

	}

}

int see_more(FILE * fp)

{

	char c;

	printf("enter your command(q space or enter):");

	while((c = getc(stdin)) != EOF)

	{

	if(c == 'q')//按q退出

		return 0;

	if(c == ' ')

		return 1;//按空格显示下一页

	if(c == 'n')

		return 2;//按n显示下一行

	}

	return 3;

}