Introduction to several output and input functions in C language

Common output functions include: * `printf()`: formatted output to the standard output device (usually the screen). * `fprintf()`: Format output to the specified file stream. * `sprintf()`: Formatted output into a string. Common input functions include: * `scanf()`: Format input from the standard input device. * `fscanf()`: Format input from the specified file stream. * `sscanf()`: Format input from a string.

In C language, functions for input and output are mainly provided by the standard input and output library . The following are several commonly used input and output functions in C language:

Output function:

1. printf(): used for formatted output. This is the most commonly used output function in C language. It can output various types of data to the standard output device (usually the screen) in a specified format.

For example:

c复制代码printf("Hello, world!\n");

2. fprintf(): Similar to printf(), but outputs to the specified file stream instead of standard output.

For example:

c复制代码FILE *fp = fopen("output.txt", "w");if (fp != NULL) {fprintf(fp, "Hello, file!\n");fclose(fp);}

3. sprintf(): Output formatted data into a string.

For example:

c复制代码char buffer[50];int a = 10;sprintf(buffer, "The value of a is %d", a);printf("%s\n", buffer);

Input function:

1. scanf(): used for formatted input. This is the most commonly used input function in C language. It can read data from the standard input device (usually the keyboard) and store it in the corresponding variable according to the specified format.

For example:

c复制代码int a;printf("Enter a number: ");scanf("%d", &a);printf("You entered: %d\n", a);

2. fscanf(): Similar to scanf(), but reads data from the specified file stream.
3. sscanf(): Read formatted data from a string.

It should be noted that these functions all involve format strings, which contain various format specifiers (such as %d for integers, %f for floating point numbers, %s for for strings, etc.). You need to choose the appropriate format specifier based on the type of data you want to input or output.

In addition, for more complex input and output requirements, C language also provides other functions and tools, such as file operation functions (fopen(), fclose(), fread(), fwrite(), etc.), character operation functions (getchar(), putchar(), gets(), puts(), etc.) etc. You can choose the appropriate function to use according to your specific needs.

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