writing a grep program

Hi,
This is not a homework problem. This is a sample test problem and I wanted to know how to do it. It would be great if someone can help me. The question is:

Write a program, similar to grep, using regcomp(3C) and regexec(3C) to search for a regular expression pattern in standard input. Program synopsis:

./p1 pattern

Simple search for regular expression pattern in standard input.

Exit status:

0 One or more matches were found
1 No matches were found
2 Syntax errors or inaccessible files (even if matches were found)

Use regcomp flags: REG_NEWLINE | REG_NOSUB
Use a function in the form:

void regex_search( regex_t *preg, FILE *fp)

to perform the search. This function will be invoked from the main program as:
regex_t reg;
...
regex_search( &reg, stdin);


I did not undertsnd how to do it as I am not very familiar with C. I am from an IC design background. It would be a great help for my exam preparations, if somebody can help me with this.

Thankyou very much.
-Cnovice

Use fgets() to read each line from a file.
Apply your regex matcher to each line.

Lather, rinse and repeat until end of file.

Quote:

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Use fgets() to read each line from a file.

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In C++? Really? I thought you were supposed to use getline or something.

fgets() is part of the c++ language isn't it?

Yeah, but it's like using printf().

and printf() is also part of the c++ language, although admittedly not commonly used in c++ programs :)

Okay, then, it's like using malloc(). :) Yeah, you can use it, but there are alternatives. (new, in the case of malloc.)

(You're not supposed to use malloc() in C++ programs because it just allocates memory, it doesn't call constructors.)

> I did not undertsnd how to do it as I am not very familiar with C.
I didn't read the board, I read this.
Hence the 'C' answer.

Moved to the 'C' board.

Quote:

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Originally Posted by dwks

Okay, then, it's like using malloc(). :) Yeah, you can use it, but there are alternatives. (new, in the case of malloc.)

(You're not supposed to use malloc() in C++ programs because it just allocates memory, it doesn't call constructors.)

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but sometimes that's all you want anyway, especially when allocating arrays of PODs or structures that contain nothing but POD data objects. However, for consistency, I agree with you that malloc() and new should not be used in the same breath (program). :rolleyes: