Preliminary learning function (3rd blog)

        C Classification of functions in language
（1）1 Library function
  2 Custom function
（2） Several simple library functions ：1 Print function printf
//2 Copy strcpy
//3 Calculation n Of k Such an operation to the power pow
//（3） Composition of functions ：（ Custom function ）
//ret_type fun_name(para1, *);
//{
//
//    statement;// Statement item
//}
//    ret_type Return type
//    fun_name Function name
//    para1 Function parameter
//         Example
//         Write a function to find the maximum value of two integers .
//    int Add(int x , int y)
//{
//        int z = x + y;
//        return z;
//}
//    int main()
//{
//        int a = 10;
//        int b = 20;
//        int sum = Add(a, b);
//        printf("%d\n", sum);
//        return 0;
//}
// Common library functions
//    io function
//     String manipulation functions Such as strlen You can find the length of the string , Of course ,sizeof It's fine too
//     Memory manipulation function Such as memste
//     Time / Date function Such as time
//     Mathematical functions
//     Other functions
#include<string.h>
//int main()
//{
//    char arr1[] = "bit";
//    char arr2[] = "###########";
//    strcpy(arr2, arr1);
//    // take \0 It's also copied
//    printf("%s\n", arr2);
//    return 0;
//}
int main()
{
    char arr[] = "hello world";
    memset(arr, '*', 5);
//memste- Memory set - Set up
    printf("%s\n", arr);

    return 0;
}
www.cplusplus.com
http://en.cppreference.com
English is very important , At least you should understand the literature .