I am trying to figure out how to create an array of strings (considering I know the max length of each string).
char** strings = NULL;
strings = malloc (5*sizeof(char*));
Once I did that, how can I just fill the array without the need to allocate each string separately? Lets say I know the max length of a string is 20, how to I set it?
After the allocation of the string I wish to do the following:
strings[0] = "string";
strings[1] = "another string";
etc.
Thanks
You can declare an array of pointers to char and then assign string literals to those pointers
char *strings[5];
strings[0] = "string";
strings[1] = "another string";
/* ... */
But note that, these strings will be immutable.
You can also use an array of char arrays
char strings[5][20]; // As you know max length of string is 20
strcpy(strings[0], "string");
strcpy(strings[1], "another string");
/* ... */
One of the advantage of latter is strings will be mutable.
NULL is used to initialize pointers, so initialising all pointers to NULL can be done in first snippet by char *strings[5] = {NULL}. This is not possible in second snippet as strings[i] is an array, not a pointer. Though, char strings[5][20] = { {'\0'} }; will make all strings empty.If you know the maximum size of each line, and if you know the maximum number of lines, you could simply define a two-dimensional array of chars, i.e. char arr[5][20+1]. Then you will have reserved space for up to 5 lines, each comprising up to 20 characters (+ null char).
And you could also define a type alias representing such a line (if you like):
#define MaxLineLength 20
typedef char Line[MaxLineLength+1];
int main() {
Line input = { 0 };
scanf("%20s", input);
Line a[5] = { 0 };
strcpy(a[0], input);
strcpy(a[1], "string1");
return 0;
}
typedef char Line[MaxLineLengh+1]; : variably modified 'Line' at file scope It must be a constant in C.Line input = {}; ISO C forbids empty initializer braces This is GCC extension (or C++ ?).
char (*strings)[20+1] = malloc(5*sizeof(*strings)); strcpy(strings[0], "string");...char *strings[5] = { "string", "another string", };