Is string is an predefined data types in c?

Answer 1

No. In C string is an array of characters terminated by a null character (a character having ascii value 0).In more high level languages like C# and Java string is a predefined data type and hence limits the operation on string by some pre-defined library functions. But C provides complete control over strings.The Following step shows declaration of a string in various methods.

char str[6] = {'h' . 'e'. 'l'. 'l'. 'o'.'\0'};

One thing you need to notice is that the size of the character array should be atleast 1 greater than the number of characters in the string for accommodating the null character.

but

char str[] = "hello";

statement appends the null character automatically and no need to specify the length of the array (of course you can specify it if you want). The compiler automatically allocates the memory according to the length of the string.