How can I use insert() method of std::string in my C++ app? How can I insert a string into another string? Can we insert a char array into a string? How can I insert number of chars into a string? Is it possible to insert a substring of a string into another string? Here are the answers with C++ examples.
Table of Contents
What is a string in a C++ app?
In a C++, app in addition to int, float, double there is another data type, string, that we use for alphanumeric variables. In C++ there are several typedefs for common character types are provided: String types are defined in header
strings are the string class for byte characters represented with the keyword string. Alphanumeric characters are stored and displayed in string forms. In other words, string stores alphanumeric text with 1-byte chars, called ASCII chars. Strings are the instantiation of the basic_string class template that uses char as the character type. We can define a string as below,
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std::string str = "This is a String"; |
string has methods to assign, copy, align, replace or to operate with other strings. These methods can be used in all string methods with their appropriate syntax. We can insert a string to another string in different methods. Let’s see some of most used methods.
How to insert a string into another string in C++ with the insert() method?
insert() method of std::string, inserts the characters of string in the given range at the position index. We can use the insert() method without the range parameter, just give the insert position index (insert_position, where to insert) and the string to be inserted (insert_str). Here is the syntax of the insert() method,
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basic_string& insert( size_type insert_position, const basic_string& insert_str ); // Until C++20 |
Here is an example of how we can use insert() method in C++
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#include #include int main() { std::string s1, s2; s1 = "first string "; s2 = "and the second "; s1.insert( 6, s2 ); // Inserts s2 to the position 6 of the s1 std::cout << s1 << std::endl; getchar(); return 0; } |
and the output will be,
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first and the second string |
How to insert a string from a starting index into another string at a specific position with the C++ insert() method
insert() method of std::string, inserts the characters of string in the given range at the position index. We can use insert() method without the range parameter, just give the insert position (insert_position, where to insert,) and the string (s) to be inserted then where to start (start_from) to be copied from. Here is syntax of a insert() method that can be used with a starting index (start_from),
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basic_string& insert( size_type insert_position, const basic_string& insert_str, size_type start_from ); // Until C++20 |
Here is a example how we can use insert() method with in this given syntax, see example below,
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#include #include int main() { std::string s1, s2; s1 = "first string "; s2 = "and the insert"; s1.insert( 5, s2, 3 ); // Inserts s2 starting from 3rd char to the position 5 of the s1 std::cout << s1 << std::endl; string_insert_atposition_inrange(); getchar(); return 0; } |
and the output will be,
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first the insert string |
How to insert a String using a range into another String at a specific position with the C++ app insert() method
insert() method of std::string, inserts the characters of string in the given range at the position index. We can use insert() method without the range parameter, just give the insert position (insert_position, where to insert,) and the string (s) to be inserted then where to start (start_from) to be copied from. Here is syntax of a insert() method that can be used with a starting index (start_from),
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basic_string& insert( size_type insert_position, const basic_string& insert_str, size_type start_from, size_type numof_chars); // Until C++20 |
Here is a example how we can use insert() method with in this given syntax, see example below,
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#include #include int main() { std::string s1, s2; s1 = "first string "; s2 = "and the insert"; s1.insert( 5, s2, 3, 4 ); // Inserts 4 chars of s2 starting from 3rd char to the position 5 of the s1 std::cout << s1 << std::endl; string_insert_atposition_inrange(); getchar(); return 0; } |
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first the string |
There are many other ways to use insert methods(). Note that we can also use these insert() methods to append wstring in C++.
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