Some interesting and practical writing methods in C language

This article collects some practical writing methods, and this blog will continue to be updated and completed

Table of contents

sscanf()——read the data in the string and save it in a certain format

sprintf() - splicing strings

Bit operations - parity judgment

Bit operations - swap two numbers

Bit operations - x to the nth power

C language - implement split() function

C language - determine whether a string is all numbers

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sscanf()——read the data in the string and save it in a certain format

// #include <stdio.h>

int res = 0;
char src[10] = "1234";

// 实现 atoi() 的功能
// atoi() 和 itoa() 定义在 strlib.h 中，但是 itoa() 函数无法在 linux 中使用

sscanf(src, "%d", &res);

printf("res = %d\n", res);

sprintf() - splicing strings

// #include <stdio.h>

char res[16] = "";

sprintf(res, "%s-%d", "abc", 123);

printf("res = %s\n", res);

Bit operations - parity judgment

int res = 10;

// 10 & 1 --> 0000 1010 & 0000 0001 --> 0000 0000 最终结果为 0 , 即 10 & 1 = 0

if(res & 1)
    printf("奇数\n");

else
    printf("偶数\n");

Bit operations - swap two numbers

int a = 0, b = 1;

a ^= b;
b ^= a;
a ^= b;

printf("a = %d, b = %d\n", a, b);

Bit operations - x to the nth power

int x = 10, n = 3, res = 1;

while (n) {
    if (n & 1 != 0) 
        res *= x;
        
    x *= x;
    n = n >> 1;
}

printf("res = %d\n", res);

C language - implement split() function

// #include <string.h>

char src[20] = "123.456.789", *res = NULL;

// strtok() 拥有记忆功能，之后传入 NULL ,则会继续使用之前裁剪的数据

res = strtok(src, ".");
printf("res = %s\n", res);

while (res)
{
    res = strtok(NULL, ".");
    printf("res = %s\n", res);
}

// 输出为  123 456 789 null

C language - determine whether a string is all numbers

// #include <string.h>

char str[8] = "1234567";

if(strspn(str, "0123456789") == strlen(str)){
    printf("全数字\n");

}else{
    printf("非全数字\n");

}