How to count number of lines in a text file

Hi,

I have a question about file i/o in C, just with text files not binary. How can I count the number of lines in the file pointed to by a FILE pointer?

Thanks.

Read entire file and count how many '\n' there are.

or if you're reading the file anyway, and have a while loop for your getline function, just declare an int before the loop and use something like

Code:

---

int file_lines=0;
while(myfile != eof){
myfile.getline(your crap here);
file_lines++;
}

---

at the end of your read loop you'll also have the number of lines stored in file_lines. Regular expressions are quite useful for such tasks.

If you're using a FILE pointer, you can do the same technique RandomPerson said, except with the C file functions:

Code:

---

FILE * myFile = fopen("...", "r");

int file_lines=0;
char buffer[1024];

while ( !feof(myFile) ){
    fgets(myFile, 1024, myFile);
    file_lines++;
}

---

The one problem with this approach is that if a line has more than 1024 characters on it, you'll get an incorrect number of lines.

If you are on a linux/unix machine
you could use the wc function with the -l option for the number of lines

Code:

---

char mystring[20];
 system("wc FileName -l > xyz"); //output the contents of the wc command to a file
 char delim=' ';       
 ifstream fileHandler;
 fileHandler.open("xyz");  // opens the file
 fileHandler.getline(mystring,20,delim); //reads the first word of the file
 fileHandler.close();
 int NumOfLines=atoi(mystring);
 system("rm xyz");

---

Works for me.