How to use scanf function in C language for user input

C language is a commonly used programming language, which provides the scanf function for input operations. The scanf function can be used to read values ​​from user-entered data and then store these values ​​into variables. This article will detail how to use the scanf function and provide some specific code examples.

First, we need to understand the basic usage of the scanf function. The prototype of the scanf function is as follows:

int scanf(const char *format, ...);

Among them, format represents the input format, which is used to specify the type of input data and the format of reading. There are many specific format characters, such as "%d" represents an integer, "%f" represents a floating point number, "%c" represents a character, "%s" represents a string, etc. In format, you can also use spaces, tabs, or newlines to ignore spaces in the input until the next non-space character is found. The ellipsis "..." indicates that an indefinite number of parameters can be accepted, and each parameter corresponds to a specific format character.

The following is a simple code example that demonstrates how to use the scanf function to read an integer entered by the user and store it into a variable:

#include <stdio.h>

int main() {
  int num;
  printf("请输入一个整数：");
  scanf("%d", &num);
  printf("您输入的整数是：%d
", num);
  return 0;
}

In this example, first a The integer variable num, and then uses the printf function to prompt the user for an integer. Next, use the scanf function to read the integer entered by the user and store it into the variable num. It should be noted that in order to save the input value to the variable num, we need to add the "&" symbol before the variable name to indicate the address of the variable. Finally, use the printf function to print out the value of the variable num.

In addition to reading integers, the scanf function can also read other types of data. The following is a sample code that demonstrates how to use the scanf function to read multiple data and store it into different variables:

#include <stdio.h>

int main() {
  int num1, num2;
  float fnum;
  printf("请输入两个整数和一个浮点数：");
  scanf("%d %d %f", &num1, &num2, &fnum);
  printf("您输入的整数是：%d 和 %d
", num1, num2);
  printf("您输入的浮点数是：%f
", fnum);
  return 0;
}

In this example, two integer variables num1 and num2 are first defined, and an Floating point variable fnum. Use the printf function to prompt the user for two integers and a floating point number. Then, use the scanf function to read the data entered by the user and store it into the num1, num2, and fnum variables respectively. Note that in the format of the scanf function, spaces are used to separate each data. Finally, use the printf function to print out the input integers and floating point numbers.

In addition to basic data types, the scanf function can also read more complex data, such as strings. The following is a sample code that demonstrates how to use the scanf function to read a string:

#include <stdio.h>

int main() {
  char name[50];
  printf("请输入您的姓名：");
  scanf("%s", name);
  printf("您的姓名是：%s
", name);
  return 0;
}

In this example, a character array name is first defined to store the string entered by the user. Use the printf function to prompt the user to enter their name, and then use the scanf function to read the string entered by the user and store it in the name variable. It should be noted that for reading strings, there is no need to add the "&" symbol before the variable name, because the character array itself is an address. Finally, use the printf function to print out the entered name.

To summarize, using the scanf function can easily read data from user input and store it in the corresponding variable. We can choose the appropriate format character according to our needs, first define the variables of the corresponding type, and then use the scanf function to perform the input operation. Through continuous practice and practice, we can master the usage of scanf function and improve our ability to perform input operations in C language.

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