c - What does this define mean? #define ASSERT(exp) -

i see code in c program don't understand.

#define assert(exp) if(!(exp)){putstr("err\n");} 

please explain , show me how use it. thank you!

you should read preprocessor directives in c.

here creating macro, gets replaced during compile time value used define macro with.

for eg:

we can use

assert(<some condition or expression>) 

through out code instead of

 if(<some condition or expression>)  {     putstr("err\n");  } 

during compile time, compiler replaces assert actual condition.