lab2

#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <stdlib.h>

void printfile(char *file);
void invalidArgs();

int main(int argc, char *argv[])
{
    if (argc==1)
    {
        invalidArgs();
    }
    int i;
    int keys=0;
    for (int i = 1; i < argc; ++i)
    {
        if (argv[i][0]!='-') { printfile(argv[i]); }
        else keys++;
    }
    if (keys==argc-1)
    {
        invalidArgs();
    }
    exit(0);
    return 0;
}

void printfile(char *file){
    assert(file!=NULL);
    FILE *fp = fopen(file, "rb");
    if (!fp)
    {
        fprintf(stderr, "Can't open input file %s!\n", file);
        exit(ENOENT);
    }
    int buff;
    while ((buff=fgetc(fp)) != EOF){
        printf("%c", buff);
    }
    fclose(fp);
}

void invalidArgs(){
    fprintf(stderr, "usage: printfiles file1 [file2 ...]\n    file1, file2, etc.: files to print\n");
    exit(EINVAL);
}