Bármilyen bemeneti és kimeneti művelet végrehajtásához C++ nyelven iostream fejlécfájlokat kell használnunk. Fejlécfájl nélkül nem tudunk bemenetet fogadni a felhasználótól, és nem nyomtathatunk ki semmilyen kimenetet.

A fejlécfájl szintaxisa:

 #include #include 'iostream.h' 

Az iostream fejlécfájlban kétféle adatfolyam található

1. Bemeneti adatfolyam : Ahhoz, hogy a felhasználótól bármilyen bemenetet fogadjunk, a cin-t kell használnunk, amely a bemeneti adatfolyamhoz tartozik

A beviteli adatfolyam használatának szintaxisa:

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 std::cin>>variable_name 

Amikor a cin végrehajtódik, a kurzor leáll az adott utasításnál az érték beviteléig. A beírt érték egy változóban kerül tárolásra.

2. Kimeneti adatfolyam : A kimenet kinyomtatásához beépített függvényeket használunk a cout output folyamban

A cout szintaxisa

 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>

A cin használatához használnunk kell #beleértve mivel a cin ehhez a fejlécfájlhoz tartozik, és e nélkül hiba történik.

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Példakód a cinhez:

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

Kimenet:

Magyarázat:

A fenti kódban a cin-t használtuk a bevitelhez, így a cin használatához fejlécfájlt vettünk fel. A bemenet felvételekor a karakterlánc-bemenet a névváltozóban tárolódik.

2. Cout

A kimenet kinyomtatásához a cout kulcsszót kell használnunk, amely az iostream fejlécfájlhoz tartozik. A cout használatához a cout kulcsszót kell használnunk, majd a << és változót, vagy az utasítást kell használnunk a kimenet kinyomtatásához.

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A cout használatának szintaxisa:

 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>

Kimenet:

Magyarázat :

A fenti kódban cout utasítást használtunk az utasítás kinyomtatására. A cout utasítás használatához tartalmaznunk kell az iostream.h fejlécfájlt. A cout végrehajtása után utasítás vagy változó értéke nyomtatja ki a kimenetet. Bármilyen utasítás kinyomtatásához dupla idézőjeleket (' ') kell használnunk, és ki kell nyomtatnunk egy változó értékét; csak a változónevet kell használnunk idézőjelek nélkül (' ')

3. Cerr

A Cerr a hibák kinyomtatására szolgál C++ nyelven, amely az iostream fejlécfájlban található. Ha bármilyen hibaüzenetet ki kell nyomtatnunk a kódban, ha valamelyik feltétel nem sikerül, akkor a cerr nagyon hasznos.

A cerr szintaxisa a következő:

 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>

Kimenet:

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Magyarázat:

A fenti kódban hibát nyomtatunk. A hiba kinyomtatásához a cerr-t használjuk, amely az iostream fejlécfájlhoz tartozik. A hiba kinyomtatása előtt a hibát egy pufferben tároljuk.

Példa : Az összes bemeneti és kimeneti adatfolyamhoz

 #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>