C++ Programming Code Examples
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Using C strings: cin,=.sync, getline
/* Using C strings: cin,=.sync, getline */
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
char header[] = "C Strings\n";
int main()
{
char hello[30] = "Hello ", name[20], message[80];
cout << header << "Your first name: ";
cin >> setw(20) >> name;
strcat( hello, name);
cout << hello << endl;
cin.sync();
cout << "\nWhat is the message for today?"
<< endl;
cin.getline( message, 80);
if( strlen( message) > 0) {
for( int i=0; message[i] != '\0'; ++i)
cout << message[i] << ' ';
cout << endl;
}
return 0;
}
Concatenate strings. The strcat() function in C++ appends a copy of a string to the end of another string. It is defined in <cstring> header file. Appends a copy of the source string to the destination string. The terminating null character in destination is overwritten by the first character of source, and a null-character is included at the end of the new string formed by the concatenation of both in destination. destination and source shall not overlap. The strcat() function takes two arguments: destination and source. This function appends a copy of the character string pointed to by source to the end of string pointed to by destination. The null terminating character at the end of destination is replaced by the first character of source and the resulting character is also null terminated.
#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.
In computer programming, loops are used to repeat a block of code. For example, when you are displaying number from 1 to 100 you may want set the value of a variable to 1 and display it 100 times, increasing its value by 1 on each loop iteration. When you know exactly how many times you want to loop through a block of code, use the for loop instead of a while loop. A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.
Get string length. Returns the length of the C string str. C++ strlen() is an inbuilt function that is used to calculate the length of the string. It is a beneficial method to find the length of the string. The strlen() function is defined under the string.h header file. The strlen() takes a null-terminated byte string str as its argument and returns its length. The length does not include a null character. If there is no null character in the string, the behavior of the function is undefined.
Get line from stream into string. The cin is an object which is used to take input from the user but does not allow to take the input in multiple lines. To accept the multiple lines, we use the getline() function. It is a pre-defined function defined in a <string.h> header file used to accept a line or a string from the input stream until the delimiting character is encountered. Extracts characters from is and stores them into str until the delimitation character delim is found (or the newline character, '\n', for (2)). The extraction also stops if the end of file is reached in is or if some other error occurs during the input operation. If the delimiter is found, it is extracted and discarded (i.e. it is not stored and the next input operation will begin after it).
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.
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.
Synchronize input buffer. Synchronizes the associated stream buffer with its controlled input sequence. Specifics of the operation depend on the particular implementation of the stream buffer object associated to the stream. Internally, the function accesses the input sequence by first constructing a sentry object (with noskipws set to true). Then (if good), it calls pubsync on its associated stream buffer object (if rdbuf is null, the function returns -1 instead). Finally, it destroys the sentry object before returning. If the call to pubsync fails (i.e., it returns -1), the function sets the badbit flag, and returns -1. Otherwise it returns zero, indicating success. Notice that the called function may succeed when no action is performed, if that is the behavior defined for the stream buffer object on synchronization. Calling this function does not alter the value returned by gcount.
Set field width. Sets the field width to be used on output operations. The C++ function std::setw behaves as if member width were called with n as argument on the stream on which it is inserted/extracted as a manipulator (it can be inserted/extracted on input streams or output streams). It is used to sets the field width to be used on output operations. This manipulator is declared in header <iomanip>. This method accepts n as a parameter which is the integer argument corresponding to which the field width is to be set. This function returns an object of unspecified type. The setw function should only be used as a stream manipulator.
To store Student details like student 'name', student 'roll num', 'student age'. You have 2 ways to do it, one way is to create different variables for each data, but the downfall of
