Keywords:
Keywords are reserved words whose meaning has already been fixed to the C compiler. Each keyword is meant to perform a specific function in a program. Since keywords are referred names for a compiler, they cannot be used as variable names because if we do so, we are trying to assign a new meaning to the keyword, which is not allowed. We canoe redefine keywords. All keywords have a predefined meaning and these meanings cannot be changed. All keywords must be written in lowercase.
For example:
int age;
Here, int is a keyword that indicates age is a variable of type int (integer).
There are 32 keywords available in C.
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auto |
break |
case |
char |
const |
continue |
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default |
do |
double |
else |
enum |
extern |
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float |
for |
goto |
if |
int |
long |
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register |
return |
short |
signed |
sizeof |
static |
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struct |
switch |
typedef |
union |
unsigned |
void |
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volatile |
while |
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Identifiers:
Identifiers are user defined words. These are used to name the variables, functions, arrays, structures, etc. These names can be in uppercase letters, lowercase letter or a combination. Identifiers must be unique. They are created to give a unique name to an entity to identify it during the execution of the program.
For example:
int age;
int roll;
Here, age and roll are identifiers.
Identifier names must be different from keywords. We cannot use int as an identifier because int is a keyword.
FAQ:
- What are keywords and identifiers in C?
- What is the main difference between keywords and identifiers in C?