Linux系统下，C语言：时间转为字符数组和long整形转换为字节数组demo-优快云博客

Linux系统下，C语言：时间转为字符数组和long整形转换为字节数组demo

1, 时间转换为字符数组

#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>

#define NLMSG_MAX_SIZE 64

// Linux系统下，C语言：时间转为数组demo
int main() {

    struct timespec ts;
    long cur_time_us;
    char tx_test[NLMSG_MAX_SIZE];
    long long time_ns;
    long long time_vs;

    char test[NLMSG_MAX_SIZE] = {0x01, 0x02, '1'};

     if (clock_gettime(CLOCK_REALTIME, &ts) == 0) {
        printf("REALTIME: %lld s, %ld ns \n", (long long)ts.tv_sec, ts.tv_nsec);
        printf("REALTIME: %lld ms\n", (long long)ts.tv_sec * 1000 + ts.tv_nsec / 1000000);

        printf("sizeof(tx_test): %d\n", sizeof(tx_test));

        //memset(tx_test, 0, sizeof(tx_test));
        time_ns = (long long)ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
        snprintf(tx_test, NLMSG_MAX_SIZE, "TIME_NS=%llu", time_ns);

        time_vs = (long long)ts.tv_sec * 1000 * 1000 + ts.tv_nsec / 1000;
        snprintf(tx_test, NLMSG_MAX_SIZE, "TIME_VS=%llu", time_vs);

        printf("tx_test: %s\n", tx_test);

        for (int i = 0; tx_test[i] != '\0' && i < NLMSG_MAX_SIZE ; i ++) {
            printf("char[%d]=%c : %x \n", i, tx_test[i], tx_test[i]);
        }

        for (int i = 0; test[i] != '\0' && i < NLMSG_MAX_SIZE ; i ++) {
            printf("char[%d]=%c : %x \n", i, test[i], test[i]);
        }
     }
}

上面程序运行结果：

REALTIME: 1750147934 s, 133826268 ns 
REALTIME: 1750147934133 ms
sizeof(tx_test): 64
tx_test: TIME_VS=1750147934133826
char[0]=T : 54 
char[1]=I : 49 
char[2]=M : 4d 
char[3]=E : 45 
char[4]=_ : 5f 
char[5]=V : 56 
char[6]=S : 53 
char[7]== : 3d 
char[8]=1 : 31 
char[9]=7 : 37 
char[10]=5 : 35 
char[11]=0 : 30 
char[12]=1 : 31 
char[13]=4 : 34 
char[14]=7 : 37 
char[15]=9 : 39 
char[16]=3 : 33 
char[17]=4 : 34 
char[18]=1 : 31 
char[19]=3 : 33 
char[20]=3 : 33 
char[21]=8 : 38 
char[22]=2 : 32 
char[23]=6 : 36 
char[0]= : 1 
char[1]= : 2 
char[2]=1 : 31

2, union转换long long整型数到字节数组如下：

#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>

#define NLMSG_MAX_SIZE 64

union U64ToBytes
{
    unsigned long long u64;
    unsigned char u8[8];
};

union U32ToBytes
{
    unsigned long long u32;
    unsigned char u8[4];
};

int main() {

    struct timespec ts;
    long cur_time_us;
    char tx_test[NLMSG_MAX_SIZE];
    long long time_ns;
    long long time_vs;

    union U64ToBytes u64ToBytes;
    union U64ToBytes bytes8;

    //u64ToBytes.u64 = 162826951238;
    //u64ToBytes.u64 = 0x123456789ABCDEF0;
    u64ToBytes.u64 = 49861866; // 49861866的十六进制是：0x2F8D4EA

    for (int i = 0; i < 8 ; i++) {
        printf("U64ToBytes: Byte [%i]: 0x%x \n", i, u64ToBytes.u8[i]);
    }

    snprintf(bytes8.u8, 8, "%s", (char *)u64ToBytes.u8);
    //bytes8.u64 = 49861866;
    for (int i = 0; i < 8 ; i++) {
        printf("bytes8: Byte [%i]: 0x%x \n", i, bytes8.u8[i]);
    }
    printf("bytes8.u64: %llu \n", bytes8.u64);

    union U32ToBytes u32ToBytes;
    u32ToBytes.u8[0] = 0xEA;
    u32ToBytes.u8[1] = 0xD4;
    u32ToBytes.u8[2] = 0xF8;
    u32ToBytes.u8[3] = 0x2;
    printf("U32ToBytes: %d \n", u32ToBytes.u32);
}

运行结果如下：

U64ToBytes: Byte [0]: 0xea 
U64ToBytes: Byte [1]: 0xd4 
U64ToBytes: Byte [2]: 0xf8 
U64ToBytes: Byte [3]: 0x2 
U64ToBytes: Byte [4]: 0x0 
U64ToBytes: Byte [5]: 0x0 
U64ToBytes: Byte [6]: 0x0 
U64ToBytes: Byte [7]: 0x0 
bytes8: Byte [0]: 0xea 
bytes8: Byte [1]: 0xd4 
bytes8: Byte [2]: 0xf8 
bytes8: Byte [3]: 0x2 
bytes8: Byte [4]: 0x0 
bytes8: Byte [5]: 0x0 
bytes8: Byte [6]: 0x0 
bytes8: Byte [7]: 0x0 
bytes8.u64: 49861866 
U32ToBytes: 49861866