C语言实现Linux的more指令（version_1）

/*this is verson_1*/

#include <stdio.h>

#define PAGELEN 10
#define LINELEN 80

void do_more(FILE *);
int see_more();

int main(int argc, char *argv[])
{
FILE *fp;

if(argc == 1)
{
do_more(stdin);
}

else
{
while(--argc)
if((fp = fopen(*++argv, "r")) != NULL)
{
do_more(fp);
fclose(fp);
}
else
{
exit(1);
}
}

return 0;
}

void do_more(FILE *fp)
{
char line[LINELEN];
int num_of_lines = 0;
int reply;

while(fgets(line, LINELEN, fp))
{
if(num_of_lines == PAGELEN)
{
reply = see_more();
if(reply == 0)
break;
num_of_lines -= reply;
}

if(fputs(line, stdout) == EOF)
exit(1);
num_of_lines++;
}
}

int see_more()
{
int c;
printf("\t[more ?]:");

while((c = getchar()) != EOF)
{
if(c == 'q')
return 0;
if(c == ' ')
return PAGELEN;
if(c == '\n')
return 1;
}
}