How to use command line arguments to change a bool value [duplicate] - c

Question

I'm trying to write a program that can compare two files line by line, word by word, or character by character in C. It has to be able to read in command line options -l, -w, -i or --...
if the option is -l, it compares the files line by line.
if the option is -w, it compares the files word by word.
if the option is --, it automatically assumes that the next argument is the first filename.
if the option is -i, it compares them in a case insensitive manner.
defaults to comparing the files character by character.
It's not supposed to matter how many times the options are input as long as -w and -l aren't inputted at the same time and there are no more or less than two files.
I don't even know where to begin with parsing the command line arguments.
So this is the code that I came up with for everything. I haven't error checked it quite yet, but am I writing things in an overcomplicated manner?
/*
* Functions to compare files.
*/
int compare_line();
int compare_word();
int compare_char();
int case_insens();
/*
* Program to compare the information in two files and print message saying
* whether or not this was successful.
*/
int main(int argc, char* argv[])
{
/* Loop counter */
size_t i = 0;
/* Variables for functions */
int caseIns = 0;
int line = 0;
int word = 0;
/* File pointers */
FILE *fp1, *fp2;
/*
* Read through command-line arguments for options.
*/
for (i = 1; i < argc; i++)
{
printf("argv[%u] = %s\n", i, argv[i]);
if (argv[i][0] == '-')
{
if (argv[i][1] == 'i')
{
caseIns = 1;
}
if (argv[i][1] == 'l')
{
line = 1;
}
if (argv[i][1] == 'w')
{
word = 1;
}
if (argv[i][1] == '-')
{
fp1 = argv[i][2];
fp2 = argv[i][3];
}
else
{
printf("Invalid option.");
return 2;
}
}
else
{
fp1(argv[i]);
fp2(argv[i][1]);
}
}
/*
* Check that files can be opened.
*/
if(((fp1 = fopen(fp1, "rb")) == NULL) || ((fp2 = fopen(fp2, "rb")) == NULL))
{
perror("fopen()");
return 3;
}
else
{
if (caseIns == 1)
{
if(line == 1 && word == 1)
{
printf("That is invalid.");
return 2;
}
if(line == 1 && word == 0)
{
if(compare_line(case_insens(fp1, fp2)) == 0)
return 0;
}
if(line == 0 && word == 1)
{
if(compare_word(case_insens(fp1, fp2)) == 0)
return 0;
}
else
{
if(compare_char(case_insens(fp1,fp2)) == 0)
return 0;
}
}
else
{
if(line == 1 && word == 1)
{
printf("That is invalid.");
return 2;
}
if(line == 1 && word == 0)
{
if(compare_line(fp1, fp2) == 0)
return 0;
}
if(line == 0 && word == 1)
{
if(compare_word(fp1, fp2) == 0)
return 0;
}
else
{
if(compare_char(fp1, fp2) == 0)
return 0;
}
}
}
return 1;
if(((fp1 = fclose(fp1)) == NULL) || (((fp2 = fclose(fp2)) == NULL)))
{
perror("fclose()");
return 3;
}
else
{
fp1 = fclose(fp1);
fp2 = fclose(fp2);
}
}
/*
* Function to compare two files line-by-line.
*/
int compare_line(FILE *fp1, FILE *fp2)
{
/* Buffer variables to store the lines in the file */
char buff1 [LINESIZE];
char buff2 [LINESIZE];
/* Check that neither is the end of file */
while((!feof(fp1)) && (!feof(fp2)))
{
/* Go through files line by line */
fgets(buff1, LINESIZE, fp1);
fgets(buff2, LINESIZE, fp2);
}
/* Compare files line by line */
if(strcmp(buff1, buff2) == 0)
{
printf("Files are equal.\n");
return 0;
}
printf("Files are not equal.\n");
return 1;
}
/*
* Function to compare two files word-by-word.
*/
int compare_word(FILE *fp1, FILE *fp2)
{
/* File pointers */
FILE *fp1, *fp2;
/* Arrays to store words */
char fp1words[LINESIZE];
char fp2words[LINESIZE];
if(strtok(fp1, " ") == NULL || strtok(fp2, " ") == NULL)
{
printf("File is empty. Cannot compare.\n");
return 0;
}
else
{
fp1words = strtok(fp1, " ");
fp2words = strtok(fp2, " ");
if(fp1words == fp2words)
{
fputs(fp1words);
fputs(fp2words);
printf("Files are equal.\n");
return 0;
}
}
return 1;
}
/*
* Function to compare two files character by character.
*/
int compare_char(FILE *fp1,FILE *fp2)
{
/* Variables to store the characters from both files */
int c;
int d;
/* Buffer variables to store chars */
char buff1 [LINESIZE];
char buff2 [LINESIZE];
while(((c = fgetc(fp1))!= EOF) && (((d = fgetc(fp2))!=EOF)))
{
if(c == d)
{
if((fscanf(fp1, "%c", buff1)) == (fscanf(fp2, "%c", buff2)))
{
printf("Files have equivalent characters.\n");
return 1;
break;
}
}
}
return 0;
}
/*
* Function to compare two files in a case-insensitive manner.
*/
int case_insens(FILE *fp1, FILE *fp2, size_t n)
{
/* Pointers for files. */
FILE *fp1, *fp2;
/* Variable to go through files. */
size_t i = 0;
/* Arrays to store file information. */
char fp1store[LINESIZE];
char fp2store[LINESIZE];
while(!feof(fp1) && !feof(fp2))
{
for(i = 0; i < n; i++)
{
fscanf(fp1, "%s", fp1store);
fscanf(fp2, "%s", fp2store);
fp1store = tolower(fp1store);
fp2store = tolower(fp2store);
return 1;
}
}
return 0;
}

Answer 1

To my knowledge, the three most popular ways how to parse command line arguments in C are:
Getopt (#include <unistd.h> from the POSIX C Library), which can solve simple argument parsing tasks. If you're a bit familiar with bash, the getopt built-in of bash is based on Getopt from the GNU libc.
Argp (#include <argp.h> from the GNU C Library), which can solve more complex tasks and takes care of stuff like, for example:
-?, --help for help message, including email address
-V, --version for version information
--usage for usage message
Doing it yourself, which I don't recommend for programs that would be given to somebody else, as there is too much that could go wrong or lower quality. The popular mistake of forgetting about '--' to stop option parsing is just one example.
The GNU C Library documentation has some nice examples for Getopt and Argp.
http://www.gnu.org/software/libc/manual/html_node/Getopt.html
http://www.gnu.org/software/libc/manual/html_node/Argp.html
Example for using Getopt
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
bool isCaseInsensitive = false;
int opt;
enum { CHARACTER_MODE, WORD_MODE, LINE_MODE } mode = CHARACTER_MODE;
while ((opt = getopt(argc, argv, "ilw")) != -1) {
switch (opt) {
case 'i': isCaseInsensitive = true; break;
case 'l': mode = LINE_MODE; break;
case 'w': mode = WORD_MODE; break;
default:
fprintf(stderr, "Usage: %s [-ilw] [file...]\n", argv[0]);
exit(EXIT_FAILURE);
}
}
// Now optind (declared extern int by <unistd.h>) is the index of the first non-option argument.
// If it is >= argc, there were no non-option arguments.
// ...
}
Example for using Argp
#include <argp.h>
#include <stdbool.h>
const char *argp_program_version = "programname programversion";
const char *argp_program_bug_address = "<your#email.address>";
static char doc[] = "Your program description.";
static char args_doc[] = "[FILENAME]...";
static struct argp_option options[] = {
{ "line", 'l', 0, 0, "Compare lines instead of characters."},
{ "word", 'w', 0, 0, "Compare words instead of characters."},
{ "nocase", 'i', 0, 0, "Compare case insensitive instead of case sensitive."},
{ 0 }
};
struct arguments {
enum { CHARACTER_MODE, WORD_MODE, LINE_MODE } mode;
bool isCaseInsensitive;
};
static error_t parse_opt(int key, char *arg, struct argp_state *state) {
struct arguments *arguments = state->input;
switch (key) {
case 'l': arguments->mode = LINE_MODE; break;
case 'w': arguments->mode = WORD_MODE; break;
case 'i': arguments->isCaseInsensitive = true; break;
case ARGP_KEY_ARG: return 0;
default: return ARGP_ERR_UNKNOWN;
}
return 0;
}
static struct argp argp = { options, parse_opt, args_doc, doc, 0, 0, 0 };
int main(int argc, char *argv[])
{
struct arguments arguments;
arguments.mode = CHARACTER_MODE;
arguments.isCaseInsensitive = false;
argp_parse(&argp, argc, argv, 0, 0, &arguments);
// ...
}
Example for Doing it Yourself
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
bool isCaseInsensitive = false;
enum { CHARACTER_MODE, WORD_MODE, LINE_MODE } mode = CHARACTER_MODE;
size_t optind;
for (optind = 1; optind < argc && argv[optind][0] == '-'; optind++) {
switch (argv[optind][1]) {
case 'i': isCaseInsensitive = true; break;
case 'l': mode = LINE_MODE; break;
case 'w': mode = WORD_MODE; break;
default:
fprintf(stderr, "Usage: %s [-ilw] [file...]\n", argv[0]);
exit(EXIT_FAILURE);
}
}
argv += optind;
// *argv points to the remaining non-option arguments.
// If *argv is NULL, there were no non-option arguments.
// ...
}
Disclaimer: I am new to Argp, the example might contain errors.

Answer 2

Use getopt(), or perhaps getopt_long().
int iflag = 0;
enum { WORD_MODE, LINE_MODE } op_mode = WORD_MODE; // Default set
int opt;
while ((opt = getopt(argc, argv, "ilw") != -1)
{
switch (opt)
{
case 'i':
iflag = 1;
break;
case 'l':
op_mode = LINE_MODE;
break;
case 'w':
op_mode = WORD_MODE;
break;
default:
fprintf(stderr, "Usage: %s [-ilw] [file ...]\n", argv[0]);
exit(EXIT_FAILURE);
}
}
/* Process file names or stdin */
if (optind >= argc)
process(stdin, "(standard input)", op_mode);
else
{
int i;
for (i = optind; i < argc; i++)
{
FILE *fp = fopen(argv[i], "r");
if (fp == 0)
fprintf(stderr, "%s: failed to open %s (%d %s)\n",
argv[0], argv[i], errno, strerror(errno));
else
{
process(fp, argv[i], op_mode);
fclose(fp);
}
}
}
Note that you need to determine which headers to include (I make it 4 that are required), and the way I wrote the op_mode type means you have a problem in the function process() - you can't access the enumeration down there. It's best to move the enumeration outside the function; you might even make op_mode a file-scope variable without external linkage (a fancy way of saying static) to avoid passing it to the function. This code does not handle - as a synonym for standard input, another exercise for the reader. Note that getopt() automatically takes care of -- to mark the end of options for you.
I've not run any version of the typing above past a compiler; there could be mistakes in it.
For extra credit, write a (library) function:
int filter(int argc, char **argv, int idx, int (*function)(FILE *fp, const char *fn));
which encapsulates the logic for processing file name options after the getopt() loop. It should handle - as standard input. Note that using this would indicate that op_mode should be a static file scope variable. The filter() function takes argc, argv, optind and a pointer to the processing function. It should return 0 (EXIT_SUCCESS) if it was able to open all the files and all invocations of the function reported 0, otherwise 1 (or EXIT_FAILURE). Having such a function simplifies writing Unix-style 'filter' programs that read files specified on the command line or standard input.

Answer 3

I've found Gengetopt to be quite useful - you specify the options you want with a simple configuration file, and it generates a .c/.h pair that you simply include and link with your application. The generated code makes use of getopt_long, appears to handle most common sorts of command line parameters, and it can save a lot of time.
A gengetopt input file might look something like this:
version "0.1"
package "myApp"
purpose "Does something useful."
# Options
option "filename" f "Input filename" string required
option "verbose" v "Increase program verbosity" flag off
option "id" i "Data ID" int required
option "value" r "Data value" multiple(1-) int optional
Generating the code is easy and spits out cmdline.h and cmdline.c:
$ gengetopt --input=myApp.cmdline --include-getopt
The generated code is easily integrated:
#include <stdio.h>
#include "cmdline.h"
int main(int argc, char ** argv) {
struct gengetopt_args_info ai;
if (cmdline_parser(argc, argv, &ai) != 0) {
exit(1);
}
printf("ai.filename_arg: %s\n", ai.filename_arg);
printf("ai.verbose_flag: %d\n", ai.verbose_flag);
printf("ai.id_arg: %d\n", ai.id_arg);
int i;
for (i = 0; i < ai.value_given; ++i) {
printf("ai.value_arg[%d]: %d\n", i, ai.value_arg[i]);
}
}
If you need to do any extra checking (such as ensuring flags are mutually exclusive), you can do this fairly easily with the data stored in the gengetopt_args_info struct.

Answer 4

You can use James Theiler's "opt" package.
And a flattering post with some examples of how it is so much simpler than other approaches is here:
Opt 3.19 review and upgrades

Answer 5

Docopt has a C implementation that I thought was quite
nice:
From a man-page standardized format describing command line options, docopt infers and creates an argument parser. This got started in Python; the Python version literally just parses the docstring and returns a dict. To do this in C takes a little more work, but it's clean to use and has no external dependencies.

Answer 6

There is a great general-purpose C library, libUCW, which includes neat command-line option parsing and configuration file loading.
The library also comes with good documentation and includes some other useful stuff (fast I/O, data structures, allocators, ...) but this can be used separately.
Example libUCW option parser (from the library docs)
#include <ucw/lib.h>
#include <ucw/opt.h>
int english;
int sugar;
int verbose;
char *tea_name;
static struct opt_section options = {
OPT_ITEMS {
OPT_HELP("A simple tea boiling console."),
OPT_HELP("Usage: teapot [options] name-of-the-tea"),
OPT_HELP(""),
OPT_HELP("Options:"),
OPT_HELP_OPTION,
OPT_BOOL('e', "english-style", english, 0, "\tEnglish style (with milk)"),
OPT_INT('s', "sugar", sugar, OPT_REQUIRED_VALUE, "<spoons>\tAmount of sugar (in teaspoons)"),
OPT_INC('v', "verbose", verbose, 0, "\tVerbose (the more -v, the more verbose)"),
OPT_STRING(OPT_POSITIONAL(1), NULL, tea_name, OPT_REQUIRED, ""),
OPT_END
}
};
int main(int argc, char **argv)
{
opt_parse(&options, argv+1);
return 0;
}

Answer 7

Tooting my own horn if I may, I'd also like to suggest taking a look at an option parsing library that I've written: dropt.
It's a C library (with a C++ wrapper if desired).
It's lightweight.
It's extensible (custom argument types can be easily added and have equal footing with built-in argument types).
It should be very portable (it's written in standard C) with no dependencies (other than the C standard library).
It has a very unrestrictive license (zlib/libpng).
One feature that it offers that many others don't is the ability to override earlier options. For example, if you have a shell alias:
alias bar="foo --flag1 --flag2 --flag3"
and you want to use bar but with--flag1 disabled, it allows you to do:
bar --flag1=0

Answer 8

I wrote a tiny library that parses arguments similar to POpt, which I had several issues with, called XOpt. It uses GNU-style argument parsing and has a very similar interface to POpt.
I use it from time to time with great success, and it works pretty much anywhere.

Answer 9

I wrote a command-line parser library called cmdparser
https://github.com/XUJINKAI/cmdparser/
It's fully tested and support nested sub-commands.
An example for question:
static cmdp_action_t callback(cmdp_process_param_st *params);
static bool g_line_by_line = false;
static bool g_word_by_word = false;
static bool g_case_insensitive = false;
static cmdp_command_st cmdp = {
.options = {
{'l', NULL, "line by line", CMDP_TYPE_BOOL, &g_line_by_line },
{'w', NULL, "word by word", CMDP_TYPE_BOOL, &g_word_by_word },
{'i', NULL, "case insensitive", CMDP_TYPE_BOOL, &g_case_insensitive },
{0},
},
.fn_process = callback,
};
int main(int argc, char **argv) {
return cmdp_run(argc - 1, argv + 1, &cmdp);
}
static cmdp_action_t callback(cmdp_process_param_st *params) {
if (g_line_by_line && g_word_by_word) {
return CMDP_ACT_FAIL | CMDP_ACT_SHOW_HELP;
}
// your code here...
return CMDP_ACT_OVER;
}

Answer 10

#include <stdio.h>
int main(int argc, char **argv)
{
size_t i;
size_t filename_i = -1;
for (i = 0; i < argc; i++)
{
char const *option = argv[i];
if (option[0] == '-')
{
printf("I am a flagged option");
switch (option[1])
{
case 'a':
/*someting*/
break;
case 'b':
break;
case '-':
/* "--" -- the next argument will be a file.*/
filename_i = i;
i = i + 1;
break;
default:
printf("flag not recognised %s", option);
break;
}
}
else
{
printf("I am a positional argument");
}
/* At this point, if -- was specified, then filename_i contains the index
into argv that contains the filename. If -- was not specified, then filename_i will be -1*/
}
return 0;
}

Answer 11

Instructional template for parsing command line arguments in C.
C:>programName -w -- fileOne.txt fileTwo.txt
BOOL argLine = FALSE;
BOOL argWord = FALSE;
BOOL argChar = FALSE;
char * fileName1 = NULL;
char * fileName2 = NULL;
int main(int argc, char * argv[]) {
int i;
printf("Argument count=%d\n",argc);
for (i = 0; i < argc; i++) {
printf("Argument %s\n",argv[i]);
if (strcmp(argv[i],"-l")==0) {
argLine = TRUE;
printf(" argLine=TRUE\n");
}
else if (strcmp(argv[i],"-w")==0) {
argWord = TRUE;
printf(" argWord=TRUE\n");
}
else if (strcmp(argv[i],"-c")==0) {
argChar = TRUE;
printf(" argChar=TRUE\n");
}
else if (strcmp(argv[i],"--")==0) {
if (i+1 <= argc) {
fileName1 = argv[++i];
printf(" fileName1=%s\n",fileName1);
}
if (i+1 <= argc) {
fileName2 = argv[++i];
printf(" fileName2=%s\n",fileName2);
}
}
}
return 0;
}

Answer 12

/*
Here's a rough one not relying on any libraries.
Example:
-wi | -iw //word case insensitive
-li | -il //line case insensitive
-- file //specify the first filename (you could just get the files
as positional arguments in the else statement instead)
PS: don't mind the #define's, they're just pasting code :D
*/
#ifndef OPT_H
#define OPT_H
//specify option requires argument
#define require \
optarg = opt_pointer + 1; \
if (*optarg == '\0') \
{ \
if (++optind == argc) \
goto opt_err_arg; \
else \
optarg = argv[optind]; \
} \
opt_pointer = opt_null_terminator;
//start processing argv
#define opt \
int optind = 1; \
char *opt_pointer = argv[1]; \
char *optarg = NULL; \
char opt_null_terminator[2] = {'\0','\0'}; \
if (0) \
{ \
opt_err_arg: \
fprintf(stderr,"option %c requires argument.\n",*opt_pointer); \
return 1; \
opt_err_opt: \
fprintf(stderr,"option %c is invalid.\n",*opt_pointer); \
return 1; \
} \
for (; optind < argc; opt_pointer = argv[++optind]) \
if (*opt_pointer++ == '-') \
{ \
for (;;++opt_pointer) \
switch (*opt_pointer) \
{
//stop processing argv
#define done \
default: \
if (*opt_pointer != '\0') \
goto opt_err_opt; \
else \
goto opt_next; \
break; \
} \
opt_next:; \
}
#endif //opt.h
#include <stdio.h>
#include "opt.h"
int
main (int argc, char **argv)
{
#define by_character 0
#define by_word 1
#define by_line 2
int cmp = by_character;
int case_insensitive = 0;
opt
case 'h':
puts ("HELP!");
break;
case 'v':
puts ("fileCMP Version 1.0");
break;
case 'i':
case_insensitive = 1;
break;
case 'w':
cmp = by_word;
break;
case 'l':
cmp = by_line;
break;
case '-':required
printf("first filename: %s\n", optarg);
break;
done
else printf ("Positional Argument %s\n", argv[optind]);
return 0;
}

Answer 13

Okay, that's the start of long story - made short
abort parsing a command line in C ...
/**
* Helper function to parse the command line
* #param argc Argument Counter
* #param argv Argument Vector
* #param prog Program Instance Reference to fill with options
*/
bool parseCommandLine(int argc, char* argv[], DuplicateFileHardLinker* prog) {
bool pathAdded = false;
// Iterate over all arguments...
for (int i = 1; i<argc; i++) {
// Is argv a command line option?
if (argv[i][0] == '-' || argv[i][0] == '/') {
// ~~~~~~ Optionally Cut that part vvvvvvvvvvvvv for sake of simplicity ~~~~~~~
// Check for longer options
if (stricmp( &argv[i][1], "NoFileName") == 0 ||
strcmp( &argv[i][1], "q1" ) == 0 ) {
boNoFileNameLog = true;
} else if (strcmp( &argv[i][1], "HowAreYou?") == 0 ) {
logInfo( "SECRET FOUND: Well - wow I'm glad ya ask me.");
} else {
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Now here comes the main thing:
//
// Check for one-character options
while (char option = *++argv[i]) {
switch (option) {
case '?':
// Show program usage
logInfo(L"Options:");
logInfo(L" /q\t>Quite mode");
logInfo(L" /v\t>Verbose mode");
logInfo(L" /d\t>Debug mode");
return false;
// Log options
case 'q':
setLogLevel(LOG_ERROR);
break;
case 'v':
setLogLevel(LOG_VERBOSE);
break;
case 'd':
setLogLevel(LOG_DEBUG);
break;
default:
logError(L"'%s' is an illegal command line option!"
" Use /? to see valid options!", option);
return false;
} // switch one-char-option
} // while one-char-options
} // else one vs longer options
} // if isArgAnOption
//
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^ So that's it! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// What follows now is are some useful extras...
//
else {
// The command line options seems to be a path...
WCHAR tmpPath[MAX_PATH_LENGTH];
mbstowcs(tmpPath, argv[i], sizeof(tmpPath));
// Check if the path is existing!
//...
prog->addPath(tmpPath); // Comment or remove to get a working example
pathAdded = true;
}
}
// Check for parameters
if (!pathAdded) {
logError("You need to specify at least one folder to process!\n"
"Use /? to see valid options!");
return false;
}
return true;
}
int main(int argc, char* argv[]) {
try {
// Parse the command line
if ( !parseCommandLine(argc, argv, prog) ) {
return 1;
}
// I know that sample is just to show how the nicely parse command-line arguments
// So Please excuse more nice useful C-glatter that follows now...
}
catch ( LPCWSTR err ) {
DWORD dwError = GetLastError();
if ( wcslen(err) > 0 ) {
if ( dwError != 0 ) {
logError(dwError, err);
}
else {
logError(err);
}
}
return 2;
}
}
#define LOG_ERROR 1
#define LOG_INFO 0
#define LOG_VERBOSE -1
#define LOG_DEBUG -2
/** Logging level for the console output */
int logLevel = LOG_INFO;
void logError(LPCWSTR message, ...) {
va_list argp;
fwprintf(stderr, L"ERROR: ");
va_start(argp, message);
vfwprintf(stderr, message, argp);
va_end(argp);
fwprintf(stderr, L"\n");
}
void logInfo(LPCWSTR message, ...) {
if ( logLevel <= LOG_INFO ) {
va_list argp;
va_start(argp, message);
vwprintf(message, argp);
va_end(argp);
wprintf(L"\n");
}
}
Note that this version will also support combining arguments:
So instead of writing /h /s -> /hs will also work.
Sorry for being the n-th person posting here - however I wasn't really satisfied with all the stand-alone-versions I saw here.
Well, the library ones are quiet nice. So I would prefer the libUCW option parser, Arg or Getopt over a home-made ones.
Note you may change:
*++argv[i] -> (++argv*)[0]
It is longer and less cryptic, but still cryptic.
Okay, let's break it down:
argv[i]-> access i-th element in the argv-char pointer field
++*... -> will forward the argv-pointer by one char
... [0]-> will follow the pointer read the char
++(...) -> bracket are there so we'll increase the pointer and not the char value itself.
It is so nice that in C#, the pointers 'died' - long live the pointers!!

Answer 14

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int is_arg(int ac, char **argv, char *arg) {
if (ac < 2) {
return 0;
}
for(int x=1; x < ac; x++) {
if (0 == strcmp(argv[x], arg)) {
return x; // return position of arg
}
}
return 0; // arg not present
}
int main (int argc, char *argv[]) {
int z = 0;
if (argc < 2) {
printf("no args present, aborting.\n");
exit(1);
}
(z=is_arg(argc, argv, "bar")) ? printf("TRUE %d\n", z) : printf("FALSE\n");
(z=is_arg(argc, argv, "one bar")) ? printf("TRUE %d\n", z) : printf("FALSE\n");
(z=is_arg(argc, argv, "foo")) ? printf("TRUE %d\n", z) : printf("FALSE\n");
/* testing:
run: ./getopt two bar "one bar" foo
TRUE 2
TRUE 3
TRUE 4
run: ./getopt two bar one bar foo
TRUE 2
FALSE
TRUE 5
*/
return 0;
}