CODEWITHSUNDEEP
cescapingcommentsstring-literals
programmer
programmer

Reputation: 95

Escape sequence in C in string

In this code:

int main() 
{ 
   char str[]= "geeks\nforgeeks"; 
   char *ptr1, *ptr2; 
       
   ptr1 = &str[3]; 
   ptr2 = str + 5; 
   printf("%c", ++*str - --*ptr1 + *ptr2 + 2);  
   printf("%s", str);  
   
   getchar(); 
   return 0; 
}

Why does the compiler interpret \n as an escape sequence and not as two characters viz, \ and n?

On the other hand, this program does not comment out hello.

int main() 
{ 
   char str[]= "geeks/*hello*/geeks";
   printf ("%s",str);
   return 0;
}

Upvotes: 0

Views: 608

Answers (2)

Vlad from Moscow
Vlad from Moscow

Reputation: 310940

Why does the compiler interpret \n as an escape sequence and not as two characters viz, \ and n?

By the definition of the escape sequence.

The C Standard (5.2.2 Character display semantics)

2 Alphabetic escape sequences representing nongraphic characters in the execution character set are intended to produce actions on display devices as follows:

//... \n (new line) Moves the active position to the initial position of the next line.

If you want to have two separate characters \ and n then you should write for example

char str[]= "geeks\\nforgeeks";

Now there are two separate characters one of which is represented by the escape sequence '\\' and other by the symbol 'n'.

As for the second your question

On the other hand, this program does not comment out hello.

char str[]= "geeks/*hello*/geeks";

Then within a string literal symbols /* and */ do not form a comment. They are elements of the string literal.

The C Standard (6.4.9 Comments)

1 Except within a character constant, a string literal, or a comment, the characters /* introduce a comment. The contents of such a comment are examined only to identify multibyte characters and to find the characters */ that terminate it.

Upvotes: 4

IrAM
IrAM

Reputation: 1738

But that is inside a string, so how does the compiler know?

The below quotes and links are sufficient enough to understand what is an escape sequence.

From Wikipedia

In C, all escape sequences consist of two or more characters, the first of which is the backslash, \ (called the "Escape character");

Also from C11 Standard

In a character constant or string literal, members of the execution character set shall be represented by corresponding members of the source character set or by escape sequences consisting of the backslash \ followed by one or more characters. A byte with all bits set to 0, called the null character, shall exist in the basic execution character set; it is used to terminate a character string.

Upvotes: 2

Related Questions