Za izvođenje bilo kakvih ulaznih i izlaznih operacija u C++-u, moramo koristiti iostream datoteke zaglavlja. Bez datoteke zaglavlja ne možemo uzeti unos od korisnika niti ispisati bilo kakav izlaz.

Sintaksa datoteke zaglavlja:

 #include #include 'iostream.h' 

Postoje dvije vrste tokova u iostream datoteci zaglavlja

1. Ulazni tok : Da bismo uzeli bilo kakav unos od korisnika, moramo koristiti cin, koji pripada ulaznom toku

Sintaksa za korištenje ulaznog toka:

 std::cin>>variable_name 

Kada se cin izvrši, pokazivač će biti zaustavljen na određenoj izjavi sve dok se ne unese vrijednost. Unesena vrijednost bit će pohranjena u varijabli.

2. Izlazni tok : Za ispis izlaza koristimo ugrađene funkcije u izlaznom toku cout

Sintaksa za cout

 std::cout&lt;<variable_name < pre> <p>When cout is executed, the value in the variable will be printed.</p> <h3>Different operations in iostream</h3> <p> <strong>1. Cin</strong> </p> <p>Using cin, we can take input from the user and store the value in the variable. We need to use the cin keyword followed by &gt;&gt; and the variable name.</p> <p> <strong>Syntax:</strong> </p> <pre> std::cin&gt;&gt;variable_name </pre> <p>To use cin, we need to use <strong>#include </strong> as cin belongs to this header file, and without this, an error will occur.</p> <p> <strong>Example code for cin:</strong> </p> <pre> //using header file iostream #include using namespace std; int main() { string name; //cin declaration cin &gt;&gt; name; return 0; } </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above code, we used cin to take the input, so to use cin, we included header file. When the input is taken, the string input is stored in the name variable.</p> <p> <strong>2. Cout</strong> </p> <p>To print the output, we need to use the cout keyword, which belongs to the iostream header file. To use cout, we need to use the cout keyword followed by &lt;&lt; and variable or the statement to print the output.</p> <p>The syntax for using cout:</p> <pre> std::cout&lt;<variable_name < pre> <p> <strong>Example of using cout:</strong> </p> <pre> //to use the cout statement, we need to use the iostream header file #include using namespace std; int main() { //cout statement is used here to print the statement cout &lt;&lt; &apos;Hi from cout statement&apos;; return 0;} </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-2.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> :</p> <p>In the above code, we used a cout statement to print the statement. To use the cout statement, we need to include iostream.h header file. Once the cout is executed, statement or variable value will be printing the output. To print any statement, we need to use double quotes (&apos; &apos;), and to print a variable value; we need to use just the variable name without double quotes(&apos; &apos;)</p> <p> <strong>3. Cerr</strong> </p> <p>Cerr is used to print errors in C++, which is present in the iostream header file. If we need to print any error message in the code if any condition fails, then cerr is very helpful.</p> <p>The syntax for cerr is:</p> <pre> cerr&lt;<variable_name < pre> <p>Example:</p> <pre> #include using namespace std; int main() { int a; cin&gt;&gt;a; if(a%2==0){ cout&lt;<'the number entered in even number'<<endl; } else{ std::cerr << 'enter proper number' '
'; return 0; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-3.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above example, we used cin to take the input and check if the given number is even or not. If the given number is not even, we need to print an error that the given number is not an even number. We use the cerr keyword in the iostream header file to print this error.</p> <p> <strong>4. Clog:</strong> </p> <p>The clog is also used to print error messages, but unlike cerr, clog is buffered, which means the error message is stored in a buffer and then will be printed, but cerr is unbuffered and will not store the error message in the buffer. The clog also belongs to the iostream header file. As the clog is buffered, it will not show the error message immediately. The clog is preferred more than cerr when efficiency is more important.</p> <p>The syntax for clog:</p> <pre> clog&lt;<variable_name; < pre> <p> <strong>Example:</strong> </p> <pre> #include using namespace std; int main() { clog &lt;&lt; &apos;This message is stored in the buffer&apos;; return 0; } </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-4.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above code, we are printing an error. To print this error, we use cerr, which belongs to the iostream header file. Before printing the error, we store the error in a buffer.</p> <p> <strong>Example</strong> : For all the input and output streams</p> <pre> #include using namespace std; int main() { int a; string b; cin&gt;&gt;a; if(a%2==0){ cout&lt;<'the number entered is even enter a name'<>b; cout&lt; <b; } else{ std::cerr << 'enter even number' '
'; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-5.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> : In the above code, we used all the input and output streams in the iostream.h header file.</p> <hr></b;></'the></pre></variable_name;></pre></'the></pre></variable_name></pre></variable_name></pre></variable_name>

Da bismo koristili cin, moramo koristiti #uključi jer cin pripada ovoj datoteci zaglavlja, a bez toga će se pojaviti pogreška.

Primjer koda za cin:

 //using header file iostream #include using namespace std; int main() { string name; //cin declaration cin >> name; return 0; } 

Izlaz:

Obrazloženje:

U gornjem kodu koristili smo cin za preuzimanje ulaza, tako da smo koristili cin, uključili smo datoteku zaglavlja. Kada se unese unos, unos niza pohranjuje se u varijablu imena.

2. Cout

Za ispis izlaza moramo upotrijebiti ključnu riječ cout, koja pripada iostream datoteci zaglavlja. Da bismo koristili cout, trebamo koristiti ključnu riječ cout iza koje slijedi << i varijabla ili naredba za ispis izlaza.

Sintaksa za korištenje cout:

int za char

 std::cout&lt;<variable_name < pre> <p> <strong>Example of using cout:</strong> </p> <pre> //to use the cout statement, we need to use the iostream header file #include using namespace std; int main() { //cout statement is used here to print the statement cout &lt;&lt; &apos;Hi from cout statement&apos;; return 0;} </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-2.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> :</p> <p>In the above code, we used a cout statement to print the statement. To use the cout statement, we need to include iostream.h header file. Once the cout is executed, statement or variable value will be printing the output. To print any statement, we need to use double quotes (&apos; &apos;), and to print a variable value; we need to use just the variable name without double quotes(&apos; &apos;)</p> <p> <strong>3. Cerr</strong> </p> <p>Cerr is used to print errors in C++, which is present in the iostream header file. If we need to print any error message in the code if any condition fails, then cerr is very helpful.</p> <p>The syntax for cerr is:</p> <pre> cerr&lt;<variable_name < pre> <p>Example:</p> <pre> #include using namespace std; int main() { int a; cin&gt;&gt;a; if(a%2==0){ cout&lt;<\'the number entered in even number\'<<endl; } else{ std::cerr << \'enter proper number\' \'
\'; return 0; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-3.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above example, we used cin to take the input and check if the given number is even or not. If the given number is not even, we need to print an error that the given number is not an even number. We use the cerr keyword in the iostream header file to print this error.</p> <p> <strong>4. Clog:</strong> </p> <p>The clog is also used to print error messages, but unlike cerr, clog is buffered, which means the error message is stored in a buffer and then will be printed, but cerr is unbuffered and will not store the error message in the buffer. The clog also belongs to the iostream header file. As the clog is buffered, it will not show the error message immediately. The clog is preferred more than cerr when efficiency is more important.</p> <p>The syntax for clog:</p> <pre> clog&lt;<variable_name; < pre> <p> <strong>Example:</strong> </p> <pre> #include using namespace std; int main() { clog &lt;&lt; &apos;This message is stored in the buffer&apos;; return 0; } </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-4.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above code, we are printing an error. To print this error, we use cerr, which belongs to the iostream header file. Before printing the error, we store the error in a buffer.</p> <p> <strong>Example</strong> : For all the input and output streams</p> <pre> #include using namespace std; int main() { int a; string b; cin&gt;&gt;a; if(a%2==0){ cout&lt;<\'the number entered is even enter a name\'<>b; cout&lt; <b; } else{ std::cerr << \'enter even number\' \'
\'; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-5.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> : In the above code, we used all the input and output streams in the iostream.h header file.</p> <hr></b;></\'the></pre></variable_name;></pre></\'the></pre></variable_name></pre></variable_name>

Izlaz:

Obrazloženje :

U gornjem kodu koristili smo naredbu cout za ispis naredbe. Da bismo koristili naredbu cout, moramo uključiti datoteku zaglavlja iostream.h. Nakon što se cout izvrši, naredba ili vrijednost varijable ispisat će izlaz. Da bismo ispisali bilo koju izjavu, moramo koristiti dvostruke navodnike (' ') i ispisati vrijednost varijable; trebamo koristiti samo naziv varijable bez dvostrukih navodnika(' ')

3. Cerr

Cerr se koristi za ispis pogrešaka u C++, koji je prisutan u iostream datoteci zaglavlja. Ako trebamo ispisati bilo koju poruku o pogrešci u kodu ako bilo koji uvjet ne uspije, tada je cerr od velike pomoći.

Sintaksa za cerr je:

 cerr&lt;<variable_name < pre> <p>Example:</p> <pre> #include using namespace std; int main() { int a; cin&gt;&gt;a; if(a%2==0){ cout&lt;<\'the number entered in even number\'<<endl; } else{ std::cerr << \'enter proper number\' \'
\'; return 0; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-3.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above example, we used cin to take the input and check if the given number is even or not. If the given number is not even, we need to print an error that the given number is not an even number. We use the cerr keyword in the iostream header file to print this error.</p> <p> <strong>4. Clog:</strong> </p> <p>The clog is also used to print error messages, but unlike cerr, clog is buffered, which means the error message is stored in a buffer and then will be printed, but cerr is unbuffered and will not store the error message in the buffer. The clog also belongs to the iostream header file. As the clog is buffered, it will not show the error message immediately. The clog is preferred more than cerr when efficiency is more important.</p> <p>The syntax for clog:</p> <pre> clog&lt;<variable_name; < pre> <p> <strong>Example:</strong> </p> <pre> #include using namespace std; int main() { clog &lt;&lt; &apos;This message is stored in the buffer&apos;; return 0; } </pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-4.webp" alt="What is include iostream in C++"> <p> <strong>Explanation:</strong> </p> <p>In the above code, we are printing an error. To print this error, we use cerr, which belongs to the iostream header file. Before printing the error, we store the error in a buffer.</p> <p> <strong>Example</strong> : For all the input and output streams</p> <pre> #include using namespace std; int main() { int a; string b; cin&gt;&gt;a; if(a%2==0){ cout&lt;<\'the number entered is even enter a name\'<>b; cout&lt; <b; } else{ std::cerr << \'enter even number\' \'
\'; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-5.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> : In the above code, we used all the input and output streams in the iostream.h header file.</p> <hr></b;></\'the></pre></variable_name;></pre></\'the></pre></variable_name>

Izlaz:

Obrazloženje:

U gornjem kodu ispisujemo pogrešku. Za ispis ove pogreške koristimo cerr, koji pripada iostream datoteci zaglavlja. Prije ispisa pogreške pohranjujemo je u međuspremnik.

Primjer : Za sve ulazne i izlazne tokove

 #include using namespace std; int main() { int a; string b; cin&gt;&gt;a; if(a%2==0){ cout&lt;<\\'the number entered is even enter a name\\'<>b; cout&lt; <b; } else{ std::cerr << \\'enter even number\\' \\'
\\'; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/23/what-is-include-iostream-c-5.webp" alt="What is include iostream in C++"> <p> <strong>Explanation</strong> : In the above code, we used all the input and output streams in the iostream.h header file.</p> <hr></b;></\\'the>