std::basic_string<CharT,Traits,Allocator>::append - cppreference.com (original) (raw)

Appends additional characters to the string.

1. Appends count copies of character ch.

2. Appends characters in the range [s, s + count).

If [s, s + count) is not a valid range, the behavior is undefined.

1. Equivalent to return append(s, Traits::length(s));.

4,5) Appends characters in a string view sv constructed from t.

• If only t is provided, all characters in sv are appended.
• If pos is also provided:
  • If count is npos, all characters in sv starting from pos are appended.
  • Otherwise, the std::min(count, sv.size() - pos) characters in sv starting from pos are appended.

1. Equivalent to std::basic_string_view<CharT, Traits> sv = t;
   return append(sv.data(), sv.size());.

2. Equivalent to std::basic_string_view<CharT, Traits> sv = t;
   return append(sv.substr(pos, count));.

6,7) Appends characters in another string str.

• If only str is provided, all characters in it are appended.
• If pos is also provided:
  • If count is npos, all characters in str starting from pos are appended.
  • Otherwise, the std::min(count, str.size() - pos) characters in str starting from pos are appended.

1. Equivalent to return append(str.data(), str.size());.

1. Equivalent to return append(basic_string(first, last, get_allocator()));.

1. Equivalent to return append(ilist.begin(), ilist.size());.

Contents

• 1 Parameters
• 2 Return value
• 3 Complexity
• 4 Exceptions
• 5 Example
• 6 Defect reports
• 7 See also

[edit] Parameters

[edit] Return value

*this

[edit] Complexity

There are no standard complexity guarantees, typical implementations behave similar to std::vector::insert().

[edit] Exceptions

If the operation would cause size() to exceed max_size(), throws std::length_error.

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit] Example

#include #include   int main() { std::string str = "std::string"; const char* cptr = "C-string"; const char carr[] = "range";   std::string result;   // 1) Append a char 3 times. // Note: This is the only overload accepting “CharT”s. result.append(3, ''); assert(result == "**");   // 2) Append a fixed-length C-string result.append(cptr, 5); assert(result == "***C-str");   // 3) Append a null-terminated C-string // Note: Because “append” returns *this, we can chain calls together. result.append(1, ' ').append(cptr); assert(result == "***C-str C-string");   // 6) Append a whole string result.append(1, ' ').append(str); assert(result == "***C-str C-string std::string");   // 7) Append part of a string result.append(str, 3, 2); assert(result == "***C-str C-string std:🧵:");   // 8) Append range result.append(&carr[2], &carr[3]); assert(result == "***C-str C-string std:🧵:n");   // 9) Append initializer list result.append({'p', 'o', 's'}); assert(result == "***C-str C-string std:🧵:npos"); }

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also