C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++

Assertions in C/C++

Assertions are the statements used to check presumptions which is made by the programmers.

Example: Assertion is used to verify whether the malloc returned by the pointer is NULL or not.

For Example:

assert(i==0);
         i++;
      assert(i==1);

Syntax:

void assert (int expression);

If the above expression returns false than source code, the file number addresses to standard error and a function is called named as abort().

Code:

#include<stdio.h>
       #include<assert.h>
       int main ()
       {
             int x=7; 
             /* few large codes accidentally let us assume x in between changes to 9     
                       */
             x = 9;
// coder assumes the value of x is 7 in remaining code
assert(x==7);
 / * remaining code */
return 0;
}

Output:

Assertion fails at x==7 

Assertion versus Normal Error Handling

Assertions are mostly used to verify rational unfeasible circumstances like they used to verify the location of a code before it started running or after running finishes. It is dissimilar to normal error handling at the time of running assertions usually disables. Therefore, it will be better if we avoid writing assertion statements like this assert () which affects.

For example: If we write assert(x=9) as x changes and we know assertions disables the changes and won’t occurs in it so it will be better if we do not use assertions like this.

Ignoring Assertions

We can eliminate assertions in C/C++ at compilation time by using Pre-processor which is named as NDEBUG.

Code:

// as NDEBUG defines the program runs excellent
           #define NDEBUG
           #include<assert.h>
           int main ()
           {
int x=8; 
                 assert(x==4);
                  return 0;
             }

In Java, assertions are disabled. To enable it, we should pass a sign to run time engine.

Assertion checks are of mainly four types:

1. Precondition Assertion

2. Postcondition Assertion

3. Invariant Assertion

4.Static Assertion

1.Precondition Assertion: The precondition assertion condition satisfies before main body execution.

2.Post_Condition Assertion: The postcondition assertion satisfies after main body execution.

3.Invariant Assertion: This invariant assertion satisfies at function of each after uninteresting region.

4.Static_ Assertion: The static assert is a keyword so while using, we can exclude header and this assert verifies at compilation time instead of running time.

static _assert (condition, diagnostic message)

If the condition is false, it prints diagnostic message.

Example:

static assert (size of(long)==8, “long must be 8 bytes”);
static assert(size of(int) ==4, “int must be 4 bytes”);
       int main ()
       {
            return 0;
        }

Compilation error

\Console app\main.cpp: error: long should be 8 types

This static error should be evaluated at the time of compilation and this static_error can be placed anywhere in the code including global space.

Advantages of static error

  1. At the time of compilation, libraries can detect common errors.
  2. C++ std library implementation detects common error of diagnosis.

Declaration Scopes

Static assert is used in three scopes i.e.

1.Namespace scope

2.Class scope

3.Block scope

1.Namespace scope:

#include<iostream>
static assert (size of(void*) == 8,
      int main ()
      {
            cout << “Assertion passed
it does not produce any error”;
            return 0;
       }

Output:

As assertion is passed it does not produce any errors.

2.Class Scope:

#include<iostream>
using namespace std;
          template <class T, int size>
          class vector {
static assert(size>3,” vector size is too small!”);
                 T m_values[size];
};
int main ()
{
          Vector<int, 4> four;
          Vector<short,2> two;
          return 0;
}

0utput:

 Due to small vector size error occurs and static assertion fails

3.Block Scope

template <TypeName T, int N>
           void f ()
           {
static assert(N>=0, “length of array ais negative.”);
                T a[N];
            }
            int main ()
            {
f < int, -1> ();
                  return 0;
              }

Output:

As length array a is negative static assertion fails error occurs

Uses of Assertions in C program

Assertion can be defined as:

#include<assert.h>
assert(condition);

always the condition should be Boolean.

Example:

int i=0;
     assert(i>=0);

From the above code, we can see that it results true because 0>=0 so at the time of execution, the code normally continues.

If the condition results to a false, the code produces an error and the code execution stops itself.

int i=0;
//false
assert(i>0);

Example of an Assertion using Loop

#include<stdio.h>
       #include<limits.h>
       #include<assert.h>
       int loop function (int a, int b) {
    //precondition assertion (a<=b)
assert(a<=b);
              int result=0;
for (int i=a; i<=b; i++) {
                    //invariant assertion
// always result is positive but sometimes it shows negative as 
                         Result overflow
//at the case of an integer assertion fails
assert(result>=0);
                    result+=i;
 }
//postcondition assertion
//always the result is positive but in the case of 0 it fails
               assert (result>0)
               return result;
}
  int main ();
              int a=3;
              int b=10;
              printf (“loop function on %d and %d gives %d\n”, a, b, loop function
              (a, b));
              int c= INT_MAX -3;
              int d=INT_MAX;
              //the invariant assertion results false in case of c and d because it 
                 Overflows
                 printf (“loop function on %d and %d gives %d\n”, c, d, loop function
                 (c, d));
                return 0;
}

Output:

Loop function upon 3 and 10 results 52 
assert loop: loop function: assertion ‘result>=0’ failed.

The result shows negative at the higher integer values due to overflow and hence invariant assertion fails, and program execution stops, and we can handle by detecting any design flaw in it.



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