how to implement a function in C

[BMWE]

Hello

given the following code:

void func(){
char *var=NULL;
str_cpy(var,"text1");
str_cpy(var,var+2);
some print(var) // result: xt1
some_free(var)
}

i should implement the str_cpy function.
how would you implement it efficiently (without memory leaks)?

 

[p.luc]

That you wrote there will end in an error for sure since you are not allocating "var" before use. If not, the "some_free(var)" will.

The correct way should be:

void func(){
char var[32];   // 32 is arbitrary and may be any number larger than the size of "text1" + 1.
str_cpy(var,"text1");
str_cpy(var,var+2);
some_print(var) // result: xt1
}

strcpy: the simplest way you can do it is like the following **broken link removed** (replace __PSTRING with char*).
or you can add a third parameter and pass a maximum quantity of chars to copy.

 

[BMWE]

That you wrote there will end in an error for sure since you are not allocating "var" before use. If not, the "some_free(var)" will.

The correct way should be:

void func(){
char var[32];   // 32 is arbitrary and may be any number larger than the size of "text1" + 1.
str_cpy(var,"text1");
str_cpy(var,var+2);
some_print(var) // result: xt1
}

strcpy: the simplest way you can do it is like the following **broken link removed** (replace __PSTRING with char*).
or you can add a third parameter and pass a maximum quantity of chars to copy.

but why to change the problem?
if i was able to change it, then i wouldn't apply for help

 

[p.luc]

what? is a problem for school? why you can't change it?
I still believe it won't work because you are passing null, not even the pointer to a pointer.
So.........

#undef NULL
#define NULL   some_malloc(32)

// implement str_cpy as said before
// then the code you wrote at the beginning.