How to make scanf() read first word of a line then jump to next line

[felix345]

I am right writing a post processor for the Grep command, since the grep outputs the number of the lines that there was a hit, So I want to read the number(ie the first word of the line then jump to the next line to read the first word again.
thank for any help given

 

[marsd]

This is totally OT and I hope I don't get lambasted for it.

What you are trying to do is much harder in C than just something like this:

#!/bin/sh
lines=`grep -n "me" $1 | sed 's/:.*//g'`

for all in $lines
do
awk -v line=$all ' {
if (NR == line) {
for (i = 0 ; i <= NF ; i++) {
if (i == 1) {
print $i
}
}
}
}' $1
done

But I am interested in seeing the equivalent program
in pure C

 

[bigtamscot]

Okay, lets presume your file is text and that each line of text is terminated by a new line character.

open file to read text,
fp = fopen(filename, &quot;rt&quot;
then loop through each line of text and increment the counter like so

int counter = 0;
char str[line_length]; // string of required length
FILE *fp;

fp = fopen(filename, &quot;rt&quot;
while(fscanf(fp,&quot;%[^\n]\n&quot;, str)!=EOF)
counter++;
printf(&quot;File holds %d lines of text&quot;, counter);
// this part of the code - &quot;%[^\n]\n&quot;- will read a string of characters up to the new line character - the extra \n then discards the new line character

OKAY
if file is binary file and you know the structure of each record.

struct myrecord {
// your structure members
};

int main (void)
{
FILE *fp;
int counter;

fp = fopen(filename, &quot;rb&quot;
fseek(fp, 0L, SEEK_END);
counter = ftell(fp)/ sizeof(struct myrecord);
printf(&quot;File holds %d lines of text&quot;, counter);
// remember to reset file pointer to start of file
// before carrying out further operations on the file
fseek(fp, 0L, SEEK_SET);
// remainder of your code for whatever you require
} //end main

Hoping to get certified..in C programming.

 

[Jay1Roy]

Humm,
Well, I think there can be a better solution using just scanf with its powerful format specifier stirng. See this:

scanf("%s %[A-Za-z0-9.- ]",str_array);

This line of code is designed to read the string (word) before the first space and later on it will read all character in a void string that can contain A-Z, a-z 0-9 . (dot) and - (hyphen) characters till the end of the line.

Loop this statement and it will get you the first word from every line.

%[A-Za-z0-9.- ]

does the magic! its a specific format specifier for strings... put in the chars you want the scanf statement read for you...

I hope I got you a precise solution

have fun coding...;-)

Roy.