In C++, strncat() adds text onto the end of a C-string, but it copies no more than count characters from the source. It always writes a '\0' after the characters it copies, so it may write one more byte than count.
All three arguments are required. dest must already have room for the old text, the new characters, and that extra '\0'. The two strings must not overlap. Include <cstring>.
The third argument limits how much of the second string is added.
strncat(dest, "World", 3);| Call | What it does |
|---|---|
strncat(dest, "World", 3) | Adds at most 3 characters from World onto the end of dest. |
char* strncat(char* destination, const char* source, size_t count);| Parameter | Description |
|---|---|
| dest | Required. The C-string you add onto. It must have free space. |
| source | Required. The characters you copy from. |
| count | Required. The most characters to take from source. |
| Return Value | Description |
|---|---|
| dest | The same pointer you passed in, now holding the longer string. |
strncat()Append a short piece after "Hello ".
#include <iostream>
#include <cstring>
int main() {
char dest[50] = "Hello ";
const char* src = "World!";
strncat(dest, src, 5);
std::cout << dest << '\n';
return 0;
}count is 5, so only W o r l d is copied.'!' is not appended.'\0' is written automatically at the end.Build a short greeting from a longer source.
#include <iostream>
#include <cstring>
int main() {
char message[40] = "Hi, ";
strncat(message, "C++ Tutorial!", 3);
std::cout << message << '\n';
return 0;
}"Hi, C++".std::stringAppend a limited substring without managing a buffer.
#include <iostream>
#include <string>
int main() {
std::string text = "Hi, ";
std::string src = "C++ Tutorial!";
text.append(src, 0, 3);
std::cout << text << '\n';
return 0;
}append(src, 0, 3) takes 3 characters from index 0.'\0' or fixed array size.strncat for C APIs; prefer std::string in new C++.Compare two C-strings using at most n characters.
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