Question

Suppose that p has been declared as follows

Char *p= “abc”;

Which of the following functions calls are legal? Show the output produced by each legal call and explain why the others are illegal

Put char (p);

Putchar(*p);

Puts(p);

Puts(*p);

Suppose that str is an array of characters. Which of the following statements is not equivalent to the other three?

*str = 0;

Str[0] = ‘\0’;

Strcpy( str, “”);

Strcat(str. “”);

Answer 1

ANSWER:-

To find which of the following functions calls are legal:-

i.)putchar(p); -- illegal call. Because the function expects a character not an integer address.

ii.)putchar(*p); // legal call will print a.

iii.)puts(p) ; legal call will print whole string abc.

iv.)puts(*p) –illegal call as function expects a string not a character.

To find which of the following statements is not equivalent to the other three:-

Given that str is an array of character.

i)*str = 0;

ii ) Str[0] = ‘\0’;

iii) Strcpy( str, “”);

iv) Strcat(str. “”);

Hence, observing the four options option (iv) Strcat(str. “”); is correct one. i.e., not equivalent to the other three.

Here, options (i) , (ii) and (iii) are equivalent in terms of what they final result i.e., an empty string.

*str = 0; - This makes the pointer str (as name of any array used as a pointer to that array) store an integer value in first character of array which is not possible. So, it behaves like an empty string.

str[0] = '\0'; - It turns the first element of the character array into null character thus ending the string there itself in the beginning making it an empty string.

strcpy(str, ""); - It overwrites the existing contents of string with an empty string (containing only '\0' ). So, it becomes an empty string.

strcat(str, ""); - It is a empty string is appended after that the original string.

Thus leaving the original string in str and not an empty string. So,it is not equivalent to other three.