Reputation: 1121

C code, seems to be skipping if statements

First and foremost, I am not asking anyone to write a program for me or to do my homework for me... I have an error and I can't figure out what's causing it, and where to look to fix it.

So I'm attempting to create a program that will take a command and an input file from the command line, and, based on the command selection, perform one of several functions: either coutn the lines of the input file, count the words of the input file, or check the input file for palindromes and then compare the palindromes (if any) to a dictionary file.

Here is the code as it stands:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

void usage(char *prog_name) //usage file if input format is wrong
{
    printf("Usage: %s, <-h>|<-l>|<-w>|<-p>, <filename>\n", prog_name);
    exit(0);
}

void help(char *prog_name, char *filename) //help file for -h option
{
    printf("Welcome to the help file\n");
    printf("For number of lines, enter: <%s>, <-l>, <%s>.\n", prog_name, filename);
    printf("For number of words, enter: <%s>, <-w>, <%s>.\n", prog_name, filename);
    printf("To list the palindromes in alphabetical order, print the number of
    palindromes, and to check them against the dictionary, enter: <%s>, <-p>, <%s>\n",
    prog_name, filename);
    exit(0);
}

void fatal(char *);  //function for fatal errors
void *ec_malloc(unsigned int);  //error-checked malloc wrapper

void linecount(char *filename)  // counts the number of lines of input file
{
    char *infile;
    infile = (char *) ec_malloc(strlen(filename));
    strcpy(infile, filename);
    FILE *fp = fopen(infile, "r");

    if (fp == NULL)         
         fatal("input file does not exist");

    int ch;
    int count = 0;                                  

    do {             
    ch = fgetc(fp);
    if( ch== '\n')
            count++;
    }   
    while( ch != EOF );                                 

    printf("Total number of lines %d\n",count);
    exit(0);            
}

int main(int argc, char *argv[])
{
    if (argc < 3) //if there aren't enough arguments, display the usage file
    {
            usage(argv[0]);
    }
    else if (argv[1] == "-h") //this is the help option
    {
        help(argv[0], argv[2]);
    }
    else if (argv[1] == "-l") //this is the line count option
    {
        linecount(argv[2]);
    }
    else
    {

            fatal("skipped if functions");
    }
    return 0;
}
void fatal(char *message) //this function displays an error message and then exits
{   
    char error_message[100];
    strcpy(error_message, "[!!] Fatal Error ");
    strncat(error_message, message, 83);
    perror(error_message);
    exit(-1);
}

void *ec_malloc(unsigned int size) //wrapper function for an error checked malloc
{
    void *ptr;
    ptr = malloc(size);

    if(ptr == NULL)
        fatal("in ec_malloc() on memory allocation");

    return ptr;
}

So, when I run:

gcc -o fr filereader.c

./fr -h fevbwervrwe.txt

I get the error message stating that the if statements were skipped.

Same if I try running

./fr -l vrweqvervvq.txt

It seems the compiler is skipping over my if statements, and I honestly can't figure out why. Any help at all would be greatly appreciated.

Upvotes: 2

Answers (7)

Dabbler

Reputation: 9873

Try strcmp() instead of ==.

Upvotes: 10

Anshul garg

Reputation: 233

Try strcmp() instead of == as == compares the address where string values are stored But strcmp compares the content (string values) which is required i think

e.g. int main(){char *a="anshul";char *b="anshul";if(a==b){ printf("ok");} /comapres address where anshul is stored/ if(strcmp(a,b)){printf("ok"); /* this will compare values i.e string anshul therefore always equal but in previous case it depends whether both anshul stored on same memory or not so not a advisable thing to do

Upvotes: 1

varunl

Reputation: 20259

As already mentioned, just understand that "argv[1]" == "-h" would mean you are comparing pointers. Keep this in mind.

And another suggestion I have for you is to look at getopt(). This is used to parse command line arguments in unix, and will make your life easier and help you in writing robust code.

Upvotes: 1