C++ Programming Code Examples
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Terminate Handler
/* Terminate Handler */
#include <fstream>
#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
#include <exception>
using namespace std;
void readIntegerFile(const string& fileName, vector<int>& dest)
{
ifstream istr;
int temp;
istr.open(fileName.c_str());
if (istr.fail()) {
throw invalid_argument("");
}
while (istr >> temp) {
dest.push_back(temp);
}
if (istr.eof()) {
istr.close();
} else {
istr.close();
throw runtime_error("");
}
}
void myTerminate()
{
cout << "Uncaught exception!\n";
exit(1);
}
int main(int argc, char** argv)
{
vector<int> myInts;
const string fileName = "IntegerFile.txt";
set_terminate(myTerminate);
readIntegerFile(fileName, myInts);
for (size_t i = 0; i < myInts.size(); i++) {
cerr << myInts[i] << " ";
}
cout << endl;
return (0);
}
runtime_error class -- Base class for runtime errors. It is a runtime error exception and this class defines the type of objects thrown as exceptions to report errors that can only be detected during runtime. The runtime_error class is the base class for runtime errors, which are errors that cannot reasonably be detected by a static analysis of the code but can be revealed only at runtime. Defines a type of object to be thrown as exception. It reports errors that are due to events beyond the scope of the program and can not be easily predicted.
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.
Check whether eofbit is set. Returns true if the eofbit error state flag is set for the stream. This flag is set by all standard input operations when the End-of-File is reached in the sequence associated with the stream. Note that the value returned by this function depends on the last operation performed on the stream (and not on the next). Operations that attempt to read at the End-of-File fail, and thus both the eofbit and the failbit end up set. This function can be used to check whether the failure is due to reaching the End-of-File or to some other reason.
Add element at the end. Adds a new element at the end of the vector, after its current last element. The content of val is copied (or moved) to the new element. This effectively increases the container size by one, which causes an automatic reallocation of the allocated storage space if -and only if- the new vector size surpasses the current vector capacity. push_back() function is used to push elements into a vector from the back. The new value is inserted into the vector at the end, after the current last element and the container size is increased by 1. This function does not return any value.
Check whether either failbit or badbit is set. Returns true if either (or both) the failbit or the badbit error state flags is set for the stream. At least one of these flags is set when an error occurs during an input operation. failbit is generally set by an operation when the error is related to the internal logic of the operation itself; further operations on the stream may be possible. While badbit is generally set when the error involves the loss of integrity of the stream, which is likely to persist even if a different operation is attempted on the stream. badbit can be checked independently by calling member function bad. This function does not accept any parameter. Function returns true if badbit and/or failbit are set.
#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.
The exit function terminates the program normally. Automatic objects are not destroyed, but static objects are. Then, all functions registered with atexit are called in the opposite order of registration. The code is returned to the operating system. An exit code of 0 or EXIT_SUCCESS means successful completion. If code is EXIT_FAILURE, an indication of program failure is returned to the operating system. Other values of code are implementation-defined. Calls all functions registered with the atexit() function, and destroys C++ objects with static storage duration, all in last-in-first-out (LIFO) order. C++ objects with static storage duration are destroyed in the reverse order of the completion of their constructor. (Automatic objects are not destroyed as a result of calling exit().)
Open file. Opens the file identified by argument filename, associating it with the stream object, so that input/output operations are performed on its content. Argument mode specifies the opening mode. If the stream is already associated with a file (i.e., it is already open), calling this function fails. The file association of a stream is kept by its internal stream buffer: Internally, the function calls rdbuf()->open(filename,mode). The function clears the stream's state flags on success (setting them to goodbit). In case of failure, failbit is set.
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.
Return size. Returns the number of elements in the vector. This is the number of actual objects held in the vector, which is not necessarily equal to its storage capacity. vector::size() is a library function of "vector" header, it is used to get the size of a vector, it returns the total number of elements in the vector. The dynamic array can be created by using a vector in C++. One or more elements can be inserted into or removed from the vector at the run time that increases or decreases the size of the vector. The size or length of the vector can be counted using any loop or the built-in function named size(). This function does not accept any parameter.
In C++, vectors are used to store elements of similar data types. However, unlike arrays, the size of a vector can grow dynamically. That is, we can change the size of the vector during the execution of a program as per our requirements. Vectors are part of the C++ Standard Template Library. To use vectors, we need to include the vector header file in our program. The vector class provides various methods to perform different operations on vectors. Add Elements to a Vector: To add a single element into a vector, we use the push_back() function. It inserts an element into the end of the vector. Access Elements of a Vector: In C++, we use the index number to access the vector elements. Here, we use the at() function to access the element from the specified index.
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.
Set terminate handler function. Sets f as the terminate handler function. A terminate handler function is a function automatically called when the exception handling process has to be abandoned for some reason. This happens when no catch handler can be found for a thrown exception, or for some other exceptional circumstance that makes impossible to continue the exception handling process. Before this function is called by the program for the first time, the default behavior is to call abort. A program may explicitly call the current terminate handler function by calling terminate,
Invalid argument exception. This class defines the type of objects thrown as exceptions to report an invalid argument. It is a standard exception that can be thrown by programs. Some components of the standard library also throw exceptions of this type to signal invalid arguments. Defines a type of object to be thrown as exception. It reports errors that arise because an argument value has not been accepted.
Access element. Returns a reference to the element at position n in the vector container. A similar member function, vector::at, has the same behavior as this operator function, except that vector::at is bound-checked and signals if the requested position is out of range by throwing an out_of_range exception. Portable programs should never call this function with an argument n that is out of range, since this causes undefined behavior. Function returns the element at the specified position in the vector.
Standard output stream for errors. Object of class ostream that represents the standard error stream oriented to narrow characters (of type char). It corresponds to the C stream stderr. The standard error stream is a destination of characters determined by the environment. This destination may be shared by more than one standard object (such as cout or clog). As an object of class ostream, characters can be written to it either as formatted data using the insertion operator (operator<<) or as unformatted data, using member functions such as write. The object is declared in header <iostream> with external linkage and static duration: it lasts the entire duration of the program.
Get C string equivalent. Returns a pointer to an array that contains a null-terminated sequence of characters (i.e., a C-string) representing the current value of the string object. The basic_string::c_str() is a builtin function in C++ which returns a pointer to an array that contains a null-terminated sequence of characters representing the current value of the basic_string object. This array includes the same sequence of characters that make up the value of the basic_string object plus an additional terminating null-character at the end. This array includes the same sequence of characters that make up the value of the string object plus an additional terminating null-character ('\0') at the end. This function does not accept any parameter. Function returns a pointer to the c-string representation of the string object's value.
In while loop, condition is evaluated first and if it returns true then the statements inside while loop execute, this happens repeatedly until the condition returns false. When condition returns false, the control comes out of loop and jumps to the next statement in the program after while loop. The important point to note when using while loop is that we need to use increment or decrement statement inside while loop so that the loop variable gets changed on each iteration, and at some point condition returns false. This way we can end the execution of while loop otherwise the loop would execute indefinitely. A while loop that never stops is said to be the infinite while loop, when we give the condition in such a way so that it never returns false, then the loops becomes infinite and repeats itself indefinitely.
In C++ programming we are using the iostream standard library, it provides cin and cout methods for reading from input and writing to output respectively. To read and write from a file we are using the standard C++ library called fstream. Let us see the data types define in fstream library is: • ofstream: This data type represents the output file stream and is used to create files and to write information to files. • ifstream: This data type represents the input file stream and is used to read information from files. • fstream: This data type represents the file stream generally, and has the capabilities of both ofstream and ifstream which means it can create files, write information to files, and read information from files.
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.
Converts any string to Lowercase. Converts a string to "uppercase". Appends a string at the end of another. Appends first 'n' characters of a string at the end of another. Copies a string
Program stores the information (name, roll & marks) of 10 students using structures. In this program, a structure, student is created. This structure has three members: name ('string'),
To convert decimal number to binary number in C++, you have to enter the decimal number to convert it into 'binary number' to print the equivalent value in binary format as shown in
