Question

[Error] 'stdprn' was not declared in this scope一直出现这个，好几个地方都是这问题。高手帮忙看看

/*print_it.c-This program prints a listing with line numbers!*/
#include<stdlib.h>
#include<stdio.h>

void do_heading(char *filename);

int line=0,page=0;

int main( int argv, char *argc[] )
{
char buffer[256];
FILE*fp;

if(argv<2)
{
fprintf(stderr,"\nProper Usage is:");
fprintf(stderr,"n\nprint_it filename.ext\n");
return(1);
}

if ((fp=fopen(argc[1],"1"))==NULL)
{
fprintf(stderr,"Error opening file, %s!",argc[1]);
return(1);
}

page=0;
line=1;
do_heading(argc[1]);

while(fgets(buffer,256,fp)!=NULL)
{
if( line %55==0 )
do_heading(argc[1]);

fprintf( stdprn,"%4d:\t%s", line++,buffer );
}

fprintf( stdprn,"\f");
fclose(fp);
return 0;
}

void do_heading(char*filename)
{
page++;

if (page>1)
fprintf( stdprn,"\f" );

fprintf( stdprn,"Page:%d,%s\n\n", page, filename );
}

Answer 1

stdprn值标准打印机，它在stdio.h中没有定义，如果希望通过打印机输出，可采取自定义stdprn的方法，比如：
FILE *stdprn;
stdprn = fopen("PRN","wb");
fprintf(stdprn,"Hello, printer! \r\n");
fclose(stdprn);

追问

谢谢啊，刚才那个我把stdprn改成stdout成了，我刚开始看着书学的，下面这个我不知道怎么弄了
#include

int main(void)
{
printf("This is a program with a");
"do_it"("problem!");
return 0;
}
[Error] expression cannot be used as a function

追答

"do_it"( )没有定义，当然会报错。如果只有include，只要不是在它里面定义的函数，都不能使用，或者include进来，或者自定义。