C++ Programming Code Examples
C++ > Strings Code Examples
Program to Remove all Characters in a String Except Alphabets
/* Program to Remove all Characters in a String Except Alphabets
You will learn to remove all characters from a string (string object and C-style string) in this example.
This program takes a string (object) input from the user and removes all characters except alphabets. */
#include <iostream>
using namespace std;
int main() {
string line;
cout << "Enter a string: ";
getline(cin, line);
for(int j = 0; j < line.size(); ++j)
{
if (!((line[j] >= 'a' && line[j]<='z') || (line[j] >= 'A' && line[j]<='Z')))
{
line[j] = '\0';
}
}
cout << "Output String: " << line;
return 0;
}
Strings are objects that represent sequences of characters. The standard string class provides support for such objects with an interface similar to that of a standard container of bytes, but adding features specifically designed to operate with strings of single-byte characters. The string class is an instantiation of the basic_string class template that uses char (i.e., bytes) as its character type, with its default char_traits and allocator types. Note that this class handles bytes independently of the encoding used: If used to handle sequences of multi-byte or variable-length characters (such as UTF-8), all members of this class (such as length or size), as well as its iterators, will still operate in terms of bytes (not actual encoded characters).
In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++: • if statement, • if...else statement, • if...else if...else statement, The if statement evaluates the condition inside the parentheses ( ). If the condition evaluates to true, the code inside the body of if is executed. If the condition evaluates to false, the code inside the body of if is skipped.
Relational operators for string. Performs the appropriate comparison operation between the string objects lhs and rhs. The functions use string::compare for the comparison. These operators are overloaded in header <string>. If strings are compared using relational operators then, their characters are compared lexicographically according to the current character traits, means it starts comparison character by character starting from the first character until the characters in both strings are equal or a NULL character is encountered.
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Return length of string. Returns the length of the string, in terms of bytes. This is the number of actual bytes that conform the contents of the string, which is not necessarily equal to its storage capacity. Note that string objects handle bytes without knowledge of the encoding that may eventually be used to encode the characters it contains. Therefore, the value returned may not correspond to the actual number of encoded characters in sequences of multi-byte or variable-length characters (such as UTF-8). Both string::size and string::length are synonyms and return the same value.
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Consider a situation, when we have two persons with the same name, jhon, in the same class. Whenever we need to differentiate them definitely we would have to use some additional information along with their name, like either the area, if they live in different area or their mother's or father's name, etc. Same situation can arise in your C++ applications. For example, you might be writing some code that has a function called xyz() and there is another library available which is also having same function xyz(). Now the compiler has no way of knowing which version of xyz() function you are referring to within your code.
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.
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To get the IP address of your computer in c++ programming, use the function system() and place the command 'ipconfig' after providing the full path of 'System32' i.e., C:\\Windows\\
Displaying the "Topological Sort Method" of finding whether a given graph contains cycle or not using Kosaraju's Algorithm. Enter the source and destination. Cycles exist in graph.
