Various counts on a text file

/* counts.c - It contains a program that is given as command parameter
*            the name of a text file, say, temp.dat. It will read each line
*            of temp.dat and print out in correspondence the number of
*            characters and words on that line. At the end it will print
*            out the number of lines that were read.
*/

#include <stdio.h>

int main (int argc, char *argv[]){
FILE *fp;
int nchars, nwords, nlines;
int lastnblank;    /* 0 iff the last character was a space */
char c;

if(argc!=2){
printf("Usage: %s filename\n", argv[0]);
exit(0);
}
if((fp=fopen(argv[1],"r"))==NULL){
perror("fopen");
exit(0);
}
nchars=nwords=nlines=lastnblank=0;
while((c=getc(fp))!=EOF){
nchars++;
if (c=='\n'){
if (lastnblank)
nwords++;
printf("words=%d, characters=%d\n", nwords, nchars);
nchars=nwords=lastnblank=0;
nlines++;
}else{
if (((c==' ')||(c=='\t'))&(lastnblank))
nwords++;
lastnblank=((c!=' ')&&(c!='\t'));
}
}
printf("lines=%d\n", nlines);
fclose(fp);
}