Can't figure out pointer/array/string in C

Question

I am new to C and I have no idea how to handle this array:

char *args[MAX_LINE/2 + 1];

What does this line mean exactly? Is it a pointer to an array of chars? The assignment given with this was to fill this array with multiple string tokens, but I don't understand how a char pointer can store a whole string?

it's an array of chars, sized to be MAX_LINE/2 + 1, e.g. 50/2 + 1 -> 26. — Marc B
– Marc B, Commented Mar 3, 2014 at 3:48
It is an array of char pointers. The size is MAX_LINE/2 +1 — Ed Heal
– Ed Heal, Commented Mar 3, 2014 at 3:50

Ed Swangren · Accepted Answer · 2014-03-03 03:56:32Z

5

char *args[MAX_LINE/2 + 1];

args is an array of pointer to char of size MAX_LINE / 2 + 1. Each element is a char*, i.e., each element may be a string. You'll have to initialize them though (i.e., point them somewhere valid.) For example, to read from stdin:

args[0] = malloc(some_size);
/* read a string from standard input */
fgets(args[0], some_size, stdin);

edited Mar 3, 2014 at 3:56

answered Mar 3, 2014 at 3:50

Ed Swangren

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5 Comments

keshlam Over a year ago

... which may be being used as an array of strings; we'd have to see what values are being put into it.

user3373372 Over a year ago

how do I go about storing strings into this array?

Ed Swangren Over a year ago

@user3373372: Allocate each element with malloc and copy them in, point them to some other string, etc. However you would populate any string in C. Added an example

user3373372 Over a year ago

@Ed S. so I tried args[0] = malloc(70); but the compiler says "incompatible implicit declaration of built-in function âmallocâ". Am I missing something?

Ed Swangren Over a year ago

@user3373372: #include <stdlib.h>. You need to include the declarations for the functions you use. You'll need stdio.h for fgets. It's all in the documentation.

bit · Accepted Answer · 2014-03-03 03:53:00Z

0

That is basically an array of pointers. Each of the pointer points to a location that holds a char .

Take a look here for more details on handling it. http://www.tutorialspoint.com/cprogramming/c_array_of_pointers.htm

answered Mar 3, 2014 at 3:53

bit

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