Learn C++

• Both functions insert the characters of str into the string at index
• Both function return *this so they can be “chained”.
• Both functions throw out_of_range if index is invalid
• Both functions throw a length_error exception if the result exceeds the maximum number of characters.
• In the C-style string version, str must not be NULL.

Sample code:

string sString("aaaa");
cout << sString << endl;

sString.insert(2, string("bbbb"));
cout << sString << endl;

sString.insert(4, "cccc");
cout << sString << endl;

Output:

aaaa
aabbbbaa
aabbccccbbaa

• This function inserts num characters str, starting from startindex, into the string at index.
• Returns *this so it can be “chained”.
• Throws an out_of_range if index or startindex is out of bounds
• Throws a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("aaaa");

const string sInsert("01234567");
sString.insert(2, sInsert, 3, 4); // insert substring of sInsert from index [3,7) into sString at index 2
cout << sString << endl;

Output:

aa3456aa

• Inserts len characters of str into the string at index
• Returns *this so it can be “chained”.
• Throws an out_of_range exception if the index is invalid
• Throws a length_error exception if the result exceeds the maximum number of characters.
• Ignores special characters (such as ‘\0′)

Sample code:

string sString("aaaa");

sString.insert(2, "bcdef", 3);
cout << sString << endl;

Output:

aabcdaa

• Inserts num instances of char c into the string at index
• Returns *this so it can be “chained”.
• Throws an out_of_range exception if the index is invalid
• Throws a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("aaaa");

sString.insert(2, 4, 'c');
cout << sString << endl;

Output:

aaccccaa

• The first function inserts num instances of the character c before the iterator it.
• The second inserts a single character c before the iterator it, and returns an iterator to the position of the character inserted.
• The third inserts all characters between [begin,end) before the iterator it.
• All functions throw a length_error exception if the result exceeds the maximum number of characters.

• Both functions append the characters of str to the string.
• Both function return *this so they can be “chained”.
• Both functions throw a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("one");

sString += string(" two");

string sThree(" three");
sString.append(sThree);

cout << sString << endl;

Output:

one two three

• This function appends num characters from str, starting at index, to the string.
• Returns *this so it can be “chained”.
• Throws an out_of_range if index is out of bounds
• Throws a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("one ");

const string sTemp("twothreefour");
sString.append(sTemp, 3, 5); // append substring of sTemp starting at index 3 of length 5
cout << sString << endl;

Output:

one three

• Both functions append the characters of str to the string.
• Both function return *this so they can be “chained”.
• Both functions throw a length_error exception if the result exceeds the maximum number of characters.
• str should not be NULL.

Sample code:

string sString("one");

sString += " two";
sString.append(" three");
cout << sString << endl;

Output:

one two three

• Appends the first len characters of str to the string.
• Returns *this so they can be “chained”.
• Throw a length_error exception if the result exceeds the maximum number of characters.
• Ignores special characters (including ‘\0′)

Sample code:

string sString("one");

sString.append("threefour", 5);
cout << sString << endl;

Output:

one three

This function is dangerous and its use is not recommended.

• Both functions append the the character c to the string.
• Operator += returns *this so it can be “chained”.
• Both functions throw a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("one");

sString += ' ';
sString.append('2');
cout << sString << endl;

Output:

one 2

Now you might be wondering why the name of the function is push_back() and not append(). This follows a naming convention used for stacks, where push_back() is the function that adds a single item to the end of the stack. If you envision a string as a stack of characters, using push_back() to add a single character to the end makes sense. However, the lack of an append() function is inconsistent in my view!

• Adds num occurrences of the character c to the string
• Returns *this so it can be “chained”.
• Throws a length_error exception if the result exceeds the maximum number of characters.

Sample code:

string sString("aaa");

sString.append(4, 'b');
cout << sString << endl;

Output:

aaabbbb

• Appends all characters from the range [start, end) (including start up to but not including end)
• Returns *this so it can be “chained”.
• Throws a length_error exception if the result exceeds the maximum number of characters.

• These functions assign values of various types to the string.
• These functions return *this so they can be “chained”.
• Note that there is no assign() function that takes a single char.

Sample code:

string sString;

// Assign a string value
sString = string("One");
cout << sString << endl;

const string sTwo("Two");
sString.assign(sTwo);
cout << sString << endl;

// Assign a C-style string
sString = "Three";
cout << sString << endl;

sString.assign("Four");
cout << sString << endl;

// Assign a char
sString = '5';
cout << sString << endl;

// Chain assignment
string sOther;
sString = sOther = "Six";
cout << sString << " " << sOther << endl;

Output:

One
Two
Three
Four
5
Six Six

• Assigns a substring of str, starting from index, and of length len
• Throws an out_of_range exception if the index is out of bounds
• Returns *this so it can be “chained”.

Sample code:

const string sSource("abcdefg");
string sDest;

sDest.assign(sSource, 2, 4); // assign a substring of source from index 2 of length 4
cout << sDest << endl;

Output:

cdef

• Assigns len characters from the C-style array chars
• Ignores special characters (including ‘\0′)
• Throws an length_error exception if the result exceeds the maximum number of characters
• Returns *this so it can be “chained”.

Sample code:

string sDest;

sDest.assign("abcdefg", 4);
cout << sDest << endl;

Output:

abcd

This function is potentially dangerous and it’s use is not recommended.

• Assigns len occurrences of the character c
• Throws an length_error exception if the result exceeds the maximum number of characters
• Returns *this so it can be “chained”.

Sample code:

string sDest;

sDest.assign(4, 'g');
cout << sDest << endl;

Output:

gggg

• Both functions swap the value of the two strings. The member function swaps *this and str, the global function swaps str1 and str2.
• These functions are efficient and should be used instead of assignments to perform a string swap.

Sample code:

string sStr1("red");
string sStr2("blue);

cout << sStr1 << " " << sStr2 << endl;
swap(sStr1, sStr2);
cout << sStr1 << " " << sStr2 << endl;
sStr1.swap(sStr2);
cout << sStr1 << " " << sStr2 << endl;

Output:

red blue
blue red
red blue