C language, write a function, how to define a function in C language

Isn't it over if you do a division of seconds?

A function is the interface between the user and the program, and before defining a function, it is necessary to understand the following three questions.

1) Functional implementation and algorithm selection of functions. Algorithm selection will be explained in detail in a subsequent article, and this section focuses on the functional implementation of functions. For example, the function name of the summation function can be taken as add, the function name for finding the maximum value can be taken as max, and the sorting function can be named sort.

2) Which parameters and what types need to be passed to the function, that is, function parameters.

3) The parameters and types that are returned to the caller after the function is executed, that is, the value type returned by the function.

Correspondence Definition Format.

The general format of a function definition is:

Return Type Function Name (Type Parameter 1, Type Parameter 2,...)

It can also be without parameters, when there are no parameters, the keyword void can be written or omitted in the parameter table, for the sake of standardization, for functions without parameters in the tutorial, the parameter table is written void. For example:

Type Function Name ().

Equivalent to: Type Function Name (void) Suggested Writing.

If the function does not return a type, it is of type void. For example:

void add (int x,int y)

In addition to the void type, in the body of the function, you need to explicitly use the return statement to return the value of the corresponding expression.

Correspondence return value.

The value of a function refers to the value obtained by executing the function body at the end of the call function and returning to the major function. The following table describes the return value of the function.

1) A function with a return value, the value of which is generally returned to the caller using a return statement. Its format is:

return expression;

Or. return expression;

For example: int add (int a, int b).

A function can contain one or more return statements, but only one of them can be executed each time it is called.

For example, a function to find the absolute value of an integer:

int f (int n) contains multiple return statements, but only one is executed per call.

Here's a function that uses a stack and a queue to extract the Arabic numerals in an array of strings and add them to the end of the rest of the original string in reverse order:

Example: <>

from collections import deque

def extract_and_reverse_strings(strings):

stack =

queue = deque()

result =

Traverse through an array of strings.

for string in strings:

for char in string:

Determines whether the characters are Arabic numerals.

if :else: Adds characters from the queue to the result string in their original order.

while queue:

result +=

Adds the numbers in the stack to the result string in reverse order.

while stack:

result +=

return result

Example: strings = abc", 123", def", 456"]

result = extract_and_reverse_strings(strings)

print(result) output: abcdef654321

In this function, we iterate through the array of strings and check each character, and if it's a number, we press it into the stack, otherwise we add it to the queue. Then, we add the characters in the queue to the result string in their original order, then add the numbers in the stack to the end of the result string in reverse order, and finally return the result string. This makes it possible to extract the Arabic numerals and add them to the rest of the original string in reverse order. Stuffiness.

#include

#include

#include

#include

#define max_length 100

void extract_and_reverse_strings(char** strings, int numstrings) ;

int numstrings = sizeof(strings) /sizeof(strings[0]);

extract_and_reverse_strings(strings, numstrings);

return 0;

Two character arrays, stack and queue, are used to simulate the functionality of the stack and queue, respectively. First, iterate over each string in the string array strings and check each character in an inner loop. If the character is an Arabic numeral, it is pushed into the stack; Otherwise, add it to the queue.

At the end of the old sleepy Kai loop, characters are output sequentially from the queue, and then in reverse order from the stack.

Note that the printf function is used here to output the result. You can store the results in an array of one-foot characters as needed, or make the appropriate modifications to meet your requirements.

Running the above ** will output:

fedcba987654321

This is the result of the Arabic numerals in the two strings in the string array added to the tail of the rest of the original string in reverse order.

1. Open C-Free and press Ctrl+N to create a new file.

2. Then start calling the function.

3. Press F9 for debugging and find that there is no error.

4. Press F5 to execute the program.

5. Enter the number you want to enter.

6. Press the Enter key to output the result, and check the matching result, indicating that the function call is successful.

A function is a block of statements that can be called and executed from elsewhere in the program. Here's the function definition format:

type name ( argument1, argument2, .statement

Note: type is the type of data returned by the function.

name is the name used when the function is called.

An argument is a parameter that needs to be passed in for a function call (any number of parameters can be declared). Each argument consists of a data type followed by an identifier name, just like in a variable declaration (e.g., int x). Parameters are only valid within the scope of the function and can be used like any other variable in the function, as they allow the function to pass in arguments when called, separated by commas.

statement is the content of the function. It can be a single instruction or a block of statements made up of a set of instructions. If it's a set of instructions, the block of statements must be enclosed in curly braces {}, which is the most common case.

In fact, in order to make the format of the program more uniform and clear, it is recommended to use curly braces when there is only one instruction, which is a good programming habit.

Example: Every C program has one and only one main function, and the main itself is a function. Combined with the above format, understand it for yourself.

int main()

1 Remove the left and right spaces, 2 See if there are illegal characters (characters other than specific characters) in the string, if they exist, they are invalid, otherwise continue 3

3 In reverse order, compare whether the first few characters are and the reverse order string of words, if so, it is valid, otherwise it is invalid.

Regular expression is definitely used here, and you can check out this class.