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Possible Duplicate:
Why doesn't scanf need an ampersand for strings and also works fine in printf (in C)?

In C when we use the scanf() function to get user input, we always use the & sign before the variable. For example: 

  scanf("%d", &number);
  scanf("%c", &letter);

This ensures our input is stored in proper address. But in case of a string we do not use &.

Why is that?

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tarashish
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2 Answers2

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A "string" in C is the address of a character buffer.
You want scanf to fill the memory in the buffer, which is pointed to by the variable.

In contrast, an int is a block of memory, not an address. In order for scanf to fill that memory, you need to pass its address.

SLaks
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Since the identifier buf in char buf[512]; degrades to a pointer to the first element of the array you don't need to specify a pointer to the buffer in the argument to scanf. By passing &buf the pointer passed to scanf is now a doubly-indirect pointer (it is a pointer to a pointer to the beginning of the buffer) and will likely cause the program to crash or other bad behaviour.

jmkeyes
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