C语言－昨天时间明细

#include<stdio.h>
#include <time.h>

struct{
    int y;
    int m;
    int d;
    }jintian;
	
int m[]={31,28,31,30,31,30,31,31,30,31,30,31};

int main()
{
	time_t st_now;
	struct tm *p_tmp = NULL;
	time(&st_now);
	p_tmp = localtime(&st_now);
	jintian.y = p_tmp->tm_year+1900;
	jintian.m = p_tmp->tm_mon+1;
	jintian.d = p_tmp->tm_mday; 
    
    jintian.d-=1;
    if(jintian.d<=0)
	{
		jintian.m--;
		if(jintian.m<=0)
		{
			jintian.y--;
			jintian.m+=12;
		}
        jintian.d+=m[jintian.m];
		if(jintian.m==2&&((jintian.y%4==0 && jintian.y%100!=0) || jintian.y%400==0))
		{
			jintian.d++;
		}
	}

    printf("昨天是%d年%d月%d日\n",jintian.y,jintian.m,jintian.d);
    
    return 0;
}