How can you check to see whether a symbol is defined?

Asked by Last Modified  

20 Answers

Learn C Language

Follow 1
Answer

Please enter your answer

Chetan Santha

Professional Tutor with 15 years of experience.

You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or whether it has not been defined (#ifndef).
Comments
Dislike Bookmark

Thank You for the question .... To check the symbol has been defined use the #ifdef function. Thank You, Team DishaaPro www.dishaapro.com
Comments
Dislike Bookmark

Having 17 years of teaching experience

To check whether the symbol is defined or not you have to use #ifdef or #ifndef. You can check like a simple if condition: #ifdef NAME (the course of ation i.e. your c / c++ code) #else (the course of ation i.e. your c / c++ code) #endif
Comments
Dislike Bookmark

You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or whether it has not been defined (#ifndef).
Comments
Dislike Bookmark

Software Professional Trainer with 26+ years of Experience in Software Design and Development

#ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or (#ifndef). #ifndef OS #define OS unix #endif ========= #ifdef UNIX #define OS unix #else #define OS windows #endif
Comments
Dislike Bookmark

Tutor

you can use #if def and #ifndef
Comments
Dislike Bookmark

Trainer

You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or whether it has not been defined (#ifndef).
Comments
Dislike Bookmark

You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined.
Comments
Dislike Bookmark

defined where in what scope? And where do you want to check in the source code or object file or library or executable?
Comments
Dislike Bookmark

Mathematics and Computer science guide

You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or whether it has not been defined (#ifndef). Many programmers like to ensure that their own version of NULL is defined, not someone else's. This task can be accomplished as shown here: #ifdef...
read more
You can use the #ifdef and #ifndef preprocessor directives to check whether a symbol has been defined (#ifdef) or whether it has not been defined (#ifndef). Many programmers like to ensure that their own version of NULL is defined, not someone else's. This task can be accomplished as shown here: #ifdef NULL #undef NULL #endif #define NULL (void*) 0 The first line, #ifdef NULL, checks to see whether the NULL symbol has been defined. If so, it is undefined using #undef NULL and the new definition of NULL is defined. To check whether a symbol has not been defined yet, you would use the #ifndef preprocessor directive. read less
Comments
Dislike Bookmark

View 18 more Answers

Related Questions

What is the structure of a C program?
A C program typically starts with preprocessor directives, followed by global variable declarations. It then defines functions, one of which must be the main() function, serving as the entry point. The...
Igno
0 0
5
Other than in a for statement, when is the comma operator used?
Example : int i,j; i=(10,20,30,40); j=10,20,30,40; printf("%d",i); printf("%d",j); // in this program output of i will be 40 and j will be 10 // In interviews you can face such type of comma operator related questions.
Sanjay
What is the difference between #include and #include "file" ?
#include is meant for including standard library files, where as #include "" is for the local/ custom header files.
Kajol
What are the average charges for online teaching per hour basis for computer languages like C?
Rs:600/Hr
Sumit Kumar
in c : i want run time input: data=[name:raj,age:20] output: value[0]=raj value[1]=20 i want c code
Make use of Command line argument and access using argv,argc.
Vanaraj

Now ask question in any of the 1000+ Categories, and get Answers from Tutors and Trainers on UrbanPro.com

Ask a Question

Related Lessons

Can we store different data types in a stack?
Yesterday, one of my Facebook friend asked me this question. My answer is "yes", and in this post I will discuss how could we do this.I am a great supporter of working with unions and I will be using union...

Shiladitya Munshi

0 0
0
Set 0 To Kth Bit In A Variable
The following code snippet Set 0 to Kth Bit in an variable #include int UnsetBitValue(int n, int k);int main(){ printf("%d\n\n",UnsetBitValue(255,6)); return 0;}// Set kth bit to zeroint UnsetBitValue(int...

Umasankar Natarajan

0 0
0
Functions In C Programming
A C-language program is nothing but collection of Function, these are the building blocks of a ‘C’ program. Generally, a function mans a task. “Function is a...

M Chandra Rao

0 0
0
Pro learners tip for C language
First get the concept of algorithm before heading to write your first program.

Pintu Das

0 0
0
Basic Concepts of Web Designing
An introduction to domain names, web servers, and website hosting 1)What is the web? In a nutshell, the web is a whole bunch of interconnected computers talking to one another. The computers (on the...

Dev Group

2 0
0

Recommended Articles

Lasya Infotech: An educational Training...

Lasya Infotech is a Hyderabad based IT training institute founded in 2016 by O Venkat. Believing in his innovation, passion and persistence and with a diverse blend of experience, he started his brainchild to deliver exemplary professional courses to aspiring candidates by honing their skills. Ever since the institute envisions...

Read full article >

Brilliant Academy, a reputed B. Tech Tuition...

Brilliant Academy is one of the reputed institutes for B.Tech tuition classes. This institute is specialised in delivering quality tuition classes for B.E, Engineering - all streams and Engineering diploma courses. Incorporated in 2012, Brillant Academy is a brainchild of Mr Jagadeesh. The main motto of the academy is to...

Read full article >

Why Should you Become an IT Consultant

Information technology consultancy or Information technology consulting is a specialized field in which one can set their focus on providing advisory services to business firms on finding ways to use innovations in information technology to further their business and meet the objectives of the business. Not only does...

Read full article >

What is Applications Engineering all about?

Applications engineering is a hot trend in the current IT market.  An applications engineer is responsible for designing and application of technology products relating to various aspects of computing. To accomplish this, he/she has to work collaboratively with the company’s manufacturing, marketing, sales, and customer...

Read full article >

Find C Language Classes near you
C Language Classes in Bangalore
C Language Classes in Hyderabad
C Language Classes in Delhi
C Language Classes in Pune
C Language Classes in Chennai
C Language Classes in Mumbai
C Language Classes in Kolkata
C Language Classes in Noida
C Language Classes in Gurgaon
C Language Classes in Ghaziabad

Looking for C Language Classes?

Learn from the Best Tutors on UrbanPro

Are you a Tutor or Training Institute?

Join UrbanPro Today to find students near you