Difference between revisions of "cpp/string/byte/strncat"
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m (Text replace - "cpp/string/narrow" to "cpp/string/byte") |
m (→Synopsis: unifying fmt: usually, "west-coast" pointers are used.) |
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| − | {{cpp/title| strncat}} | + | {{cpp/title|strncat}} |
| − | {{cpp/string/byte/ | + | {{cpp/string/byte/navbar}} |
| − | {{ddcl | header=cstring | | + | {{ddcl|header=cstring| |
| − | char *strncat( char *dest, const char *src, size_t count ); | + | char* strncat( char* dest, const char* src, std::size_t count ); |
}} | }} | ||
| − | Appends a byte string pointed to by {{ | + | Appends a byte string pointed to by {{c|src}} to a byte string pointed to by {{c|dest}}. At most {{c|count}} characters are copied. The resulting byte string is null-terminated. |
| + | |||
| + | The destination byte string must have enough space for the contents of both {{c|dest}} and {{c|src}} plus the terminating null character, except that the size of {{c|src}} is limited to {{c|count}}. | ||
| + | |||
| + | The behavior is undefined if the strings overlap. | ||
===Parameters=== | ===Parameters=== | ||
| − | {{ | + | {{par begin}} |
| − | {{ | + | {{par|dest|pointer to the null-terminated byte string to append to}} |
| − | {{ | + | {{par|src|pointer to the null-terminated byte string to copy from}} |
| − | {{ | + | {{par|count|maximum number of characters to copy}} |
| − | {{ | + | {{par end}} |
===Return value=== | ===Return value=== | ||
| + | {{c|dest}} | ||
| − | {{tt|dest}} | + | ===Notes=== |
| + | Because {{tt|std::strncat}} needs to seek to the end of {{c|dest}} on each call, it is inefficient to concatenate many strings into one using {{tt|std::strncat}}. | ||
===Example=== | ===Example=== | ||
| − | {{example | + | {{example |
| − | + | |code= | |
| − | + | #include <cstdio> | |
| − | | output= | + | #include <cstring> |
| + | |||
| + | int main() | ||
| + | { | ||
| + | char str[50] = "Hello "; | ||
| + | const char str2[50] = "World!"; | ||
| + | std::strcat(str, str2); | ||
| + | std::strncat(str, " Goodbye World!", 3); // may issue "truncated output" warning | ||
| + | std::puts(str); | ||
| + | } | ||
| + | |output= | ||
| + | Hello World! Go | ||
}} | }} | ||
===See also=== | ===See also=== | ||
| − | {{ | + | {{dsc begin}} |
| − | {{ | + | {{dsc inc|cpp/string/byte/dsc strcat}} |
| − | {{ | + | {{dsc inc|cpp/string/byte/dsc strcpy}} |
| − | {{ | + | {{dsc see c|c/string/byte/strncat}} |
| + | {{dsc end}} | ||
| + | |||
| + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 14:32, 6 June 2023
| Defined in header <cstring>
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| char* strncat( char* dest, const char* src, std::size_t count ); |
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Appends a byte string pointed to by src to a byte string pointed to by dest. At most count characters are copied. The resulting byte string is null-terminated.
The destination byte string must have enough space for the contents of both dest and src plus the terminating null character, except that the size of src is limited to count.
The behavior is undefined if the strings overlap.
Contents |
[edit] Parameters
| dest | - | pointer to the null-terminated byte string to append to |
| src | - | pointer to the null-terminated byte string to copy from |
| count | - | maximum number of characters to copy |
[edit] Return value
dest
[edit] Notes
Because std::strncat needs to seek to the end of dest on each call, it is inefficient to concatenate many strings into one using std::strncat.
[edit] Example
Run this code
#include <cstdio> #include <cstring> int main() { char str[50] = "Hello "; const char str2[50] = "World!"; std::strcat(str, str2); std::strncat(str, " Goodbye World!", 3); // may issue "truncated output" warning std::puts(str); }
Output:
Hello World! Go
[edit] See also
| concatenates two strings (function) | |
| copies one string to another (function) | |
| C documentation for strncat
| |
