Programming Forums > Application Development > C

ivan · Jun 27th, 2006, 8:05 AM

Ok, I will try to guess what you think...

if(argc!=2)
{ ----}

I suppose that here you are trying to check if argc contains 1 argument. What would happen if the user entered more than two arguments? So, the correct way would be:

(Toggle Plain Text)

if(argc == 1)
{ ----}

Now, in the if - statement, do you want to check that i is equal to 4? If iso, if( i == 4 ) would work just fine.

I hope that helps.

DaWei · Jun 27th, 2006, 8:24 AM

Squirrel, please go back to using code tags. Ivan, some of us think he want to set this value with a command line argument, as when he invokes the program. Others think he wants to set the value with a command line argument when he invokes the COMPILER to compile the program. He hasn't addressed this issue. He has been given solutions if the first assumption is correct. He hasn't given any really definitive code snippets or expressed his needs clearly. It's all ambiguous. Good responses are difficult to come up with under the circumstances.

squirrel · Jun 27th, 2006, 8:27 AM

No u got me wrong. May be i explained it wrong.
I have a program which has a if construct:

(Toggle Plain Text)

fread(data,sizeof(data),1,fp_myfile);
if(data[0]=='8')&&(data[1]=='2'))
{
memcpy(&i,data+17,sixeof(int));

if(i == 4) // the value of "i" is not always same, so need to change the value of "i" eachtime i run the program
{
some commands;
}
else
{
some statements;
}
}

This program is hardcoded, and i need to open the program and change the value of "i" always.

I modified the program so that "i" can be taken as command line argument. I added some code lines as follows:

(Toggle Plain Text)

int i;
---
---

if(argc!=2)
{ 
printf("Error at command line");
printf("Enter value if 'i' ");
}

i=atoi(argv[1]);

Now my problem is how do i change the if construct??
fread(data,sizeof(data),1,fp_myfile);
if(data[0]=='8')&&(data[1]=='2'))
{
memcpy(&i,data+17,sixeof(int));
if(i == ??) // what do I give here, like how do i change the if construct, bcoz the value is taken from command line, its a bit confusing?? 
{
some commands;
}
else
{
some statements;
}
}

Hope the problem is understood.

thanks
Squirrel

squirrel · Jun 27th, 2006, 8:28 AM

DaWei -> Iam sorry for posting such unclear questions. But i guess I will learn it soon, as iam new in the forums.

DaWei · Jun 27th, 2006, 8:32 AM

Maybe understood. Let's presume you are now setting the value of i from the command line. Now you want to branch depending upon that value. If you don't know how your branch condition relates to the value, how the hell can we? Perhaps you could post a chart. If i is in the range blah:bleah, do this; otherwise, do that.

squirrel · Jun 27th, 2006, 8:50 AM

Thankx for the help

stevengs · Jun 27th, 2006, 9:37 AM

Quote:

Originally Posted by squirrel

DaWei -> Iam sorry for posting such unclear questions. But i guess I will learn it soon, as iam new in the forums.

The ability to convey an idea has nothing to do with being new to a forum.

Quote:

Originally Posted by squirrel

(Toggle Plain Text)

int i;
---
---

if(argc!=2)
{ 
printf("Error at command line");
printf("Enter value if 'i' ");
}

i=atoi(argv[1]);

You seem to wish to acquire input from the command line in the event that the program was called without (enough) arguments (but that is really just a wild guess). Input from the commandline in the middle of the program has nothing to do with the 'arg' variable (unless you explicitly put it in there). There are tools with varying degrees of portability (and robustness) available for getting input from the command line -> check out the stdio library.

The use of 'if' is particularly simple, but without some idea of the logic behind the program, no one will be able to help you much. For starters what does "i" represent, what do you intend to decide based apon it and what will actions will be taken? How many valid values of your particular "i" are there?

tempest · Jun 27th, 2006, 10:44 AM

It's as simple as changing your question marks to an actual number that you want i to be compared to...

Jun 27th, 2006, 8:05 AM	#21
ivan Professional Programmer Join Date: Sep 2005 Location: serbia & montenegro Posts: 484 Rep Power: 4	Ok, I will try to guess what you think... (Toggle Plain Text) if(argc!=2) { ----} if(argc!=2) { ----} I suppose that here you are trying to check if argc contains 1 argument. What would happen if the user entered more than two arguments? So, the correct way would be: (Toggle Plain Text) if(argc == 1) { ----} if(argc == 1) { ----} Now, in the if - statement, do you want to check that i is equal to 4? If iso, if( i == 4 ) would work just fine. I hope that helps.

Jun 27th, 2006, 8:24 AM	#22
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Squirrel, please go back to using code tags. Ivan, some of us think he want to set this value with a command line argument, as when he invokes the program. Others think he wants to set the value with a command line argument when he invokes the COMPILER to compile the program. He hasn't addressed this issue. He has been given solutions if the first assumption is correct. He hasn't given any really definitive code snippets or expressed his needs clearly. It's all ambiguous. Good responses are difficult to come up with under the circumstances. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 27th, 2006, 8:27 AM	#23
squirrel Newbie Join Date: Jun 2006 Posts: 11 Rep Power: 0	No u got me wrong. May be i explained it wrong. I have a program which has a if construct: (Toggle Plain Text) fread(data,sizeof(data),1,fp_myfile); if(data[0]=='8')&&(data[1]=='2')) { memcpy(&i,data+17,sixeof(int)); if(i == 4) // the value of "i" is not always same, so need to change the value of "i" eachtime i run the program { some commands; } else { some statements; } } fread(data,sizeof(data),1,fp_myfile); if(data[0]=='8')&&(data[1]=='2')) { memcpy(&i,data+17,sixeof(int)); if(i == 4) // the value of "i" is not always same, so need to change the value of "i" eachtime i run the program { some commands; } else { some statements; } } This program is hardcoded, and i need to open the program and change the value of "i" always. I modified the program so that "i" can be taken as command line argument. I added some code lines as follows: (Toggle Plain Text) int i; --- --- if(argc!=2) { printf("Error at command line"); printf("Enter value if 'i' "); } i=atoi(argv[1]); Now my problem is how do i change the if construct?? fread(data,sizeof(data),1,fp_myfile); if(data[0]=='8')&&(data[1]=='2')) { memcpy(&i,data+17,sixeof(int)); if(i == ??) // what do I give here, like how do i change the if construct, bcoz the value is taken from command line, its a bit confusing?? { some commands; } else { some statements; } } int i; --- --- if(argc!=2) { printf("Error at command line"); printf("Enter value if 'i' "); } i=atoi(argv[1]); Now my problem is how do i change the if construct?? fread(data,sizeof(data),1,fp_myfile); if(data[0]=='8')&&(data[1]=='2')) { memcpy(&i,data+17,sixeof(int)); if(i == ??) // what do I give here, like how do i change the if construct, bcoz the value is taken from command line, its a bit confusing?? { some commands; } else { some statements; } } Hope the problem is understood. thanks Squirrel

Jun 27th, 2006, 8:32 AM	#25
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Maybe understood. Let's presume you are now setting the value of i from the command line. Now you want to branch depending upon that value. If you don't know how your branch condition relates to the value, how the hell can we? Perhaps you could post a chart. If i is in the range blah:bleah, do this; otherwise, do that. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 27th, 2006, 10:44 AM	#28
tempest Programming Guru Join Date: Oct 2004 Posts: 1,041 Rep Power: 5	It's as simple as changing your question marks to an actual number that you want i to be compared to... __________________

Jun 27th, 2006, 8:28 AM	#24
squirrel Newbie Join Date: Jun 2006 Posts: 11 Rep Power: 0	DaWei -> Iam sorry for posting such unclear questions. But i guess I will learn it soon, as iam new in the forums.

Jun 27th, 2006, 8:50 AM	#26
squirrel Newbie Join Date: Jun 2006 Posts: 11 Rep Power: 0	Thankx for the help

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Programming Forums > Application Development > C

compile program with command line arguments