c - Alternative way to pass a char pointer to a function -

given source code strcpy()

char * strcpy(char *s1, const char *s2) {     char *s = s1;     while ((*s++ = *s2++) != 0);     return (s1); } 

why handing on second argument work , how in memory since not pass pointer function

char dest[100]; strcpy(dest, "helloworld"); 

in c string literals have types of character arrays. c standard (6.4.5 string literals)

6 in translation phase 7, byte or code of value 0 appended each multibyte character sequence results string literal or literals.78) the multibyte character sequence used initialize array of static storage duration , length sufficient contain sequence. character string literals, array elements have type char, , initialized individual bytes of multibyte character sequence.

also arrays rare exceptions converted pointers in expressions. c standard, 6.3.2.1 lvalues, arrays, , function designators

3 except when operand of sizeof operator or unary & operator, or string literal used initialize array, expression has type ‘‘array of type’’ converted expression type ‘‘pointer type’’ points initial element of array object , not lvalue. if array object has register storage class, behavior undefined.

thus in call

strcpy(dest, "helloworld"); 

the string literal has type char[11] converted value of type char * equal address of first character of string literal.

you write example

strcpy(dest, &"helloworld"[0]); 

or :)

strcpy(dest, &0["helloworld"]); 

or:)

strcpy(dest, &*"helloworld"); 

all 3 expressions yield address of initial element of string literal , have type char *. take account implementation-defined (usually controlled compiler options) whether

"helloworld" == "helloworld" 

is evaluated true. whether compiler allocates separate extents of memory identical string literals or store 1 copy of them.

in expression addresses of first characters of string literals compared.

if write

strcmp( "helloworld", "helloworld" ) 

then result equal 0 string literals equal each other (contain same sequence of characters)