strcpy vs sprintf

[ripe badge]

lets say I have an empty char array. I noticed that strcpy and sprintf kinda does the same thing but strcpy doesnt have formatting? is that the only difference?

[misty oxide]

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[wise acorn]

The difference is in the way you use it

with srtcpy you copy the string from one char array to a another empty char array so it would look like

// source
char src[] = "This is a string"

// destination
char des[100];

// copying the strings using strcpy
strcpy(des, src); // now des contains the string "This is a string"

while with sprintf it is direct if you know what I mean wait let me show you it is better if I do

// destination
char des[100];

sprintf(des, "This is a string");

[vocal tree]

Pretty much; I usually try to use strcpy() (or strncpy()) whenever possible, and only sprintf() (or snprintf()) whenever I need formatting

[torn tide]

strncpy 💀

[wise acorn]

yes

it is actually useful sometimes

[torn tide]

when?

[wise acorn]

tho I prefer strcpy

[wise acorn]

i cant remember of a scenario must have been a decade since I last used it I mostly use strcpy

if I need to do some like that

[sinful tundra]

If you have a char array and you always know it's size so you don't need it to be null-terminated

[torn tide]

yeah, though when do you want that?

[sinful tundra]

off the top of my head, acpica does this

[torn tide]

also here is something to consider: strncpy always writes n bytes, e.g. if there is 10 extra bytes of capacity it will write 10 null terminators

[sinful tundra]

e.g the ACPI spec limits identifiers to 4 chars, so there's no point in accounting for more

[sinful tundra]

True, but I don't see that as much of a problem

[torn tide]

I think most uses of strncpy don't actually involve this case, a lot of people use it as a bounded strcpy when that isn't really what it is for

[sinful tundra]

Yea that's fair enough
It's pretty specific

[torn tide]

I've seen several examples of where people manually write a null terminator after the strncpy because they realize that issue exists, but don't realize that strncpy isn't made for what they're doing

snprintf actually works as a better bounded strcpy thinking about it lol

[sinful tundra]

lol, yea snprintf would be better for what you're describing
I feel like a lot of things in C are misused like that