到底如何将自定义函数返回的字符串（指针）在主函数中调用？

Question

自定义函数的具体内容都没有问题，但是我想把那个string指针在主函数中调用
并且 打印出来~但是我无论怎么求，打印出的指针值总是空指针，实在想不明白~

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
char* reverse(int hdays, char hmonth[], int hyears)
{
    int tdays1,tyears,tdays2,tre;
    int days;
    int i;
    char *a[21]={"pop","no", "zip", "zotz", "tzec", "xul", "yoxkin", "mol", "chen", "yax", "zac", "ceh", "mac", "kankin", "muan", "pax", "koyab", "cumhu"};
    char *b[21]={"imix","ik","akbal","kan","chicchan","cimi","manik","lamat","muluk","ok","chuen","eb","ben","ix","mem","cib","caban","eznab","canac","ahau"};
    char *string;

    for(i=0;i<19&&strcmp(hmonth,a[i])!=0;i++);
    days=i*20+(hyears)*365+hdays+1;
    tyears=days/260;
    tre=days%260;
    tdays1=(tre%13==0)?13:tre%13;
    tdays2=(tre%20==0)?20:tre%20;
    sprintf(string,"%d %s %d",tdays1,*(b+tdays2-1),tyears);
    return string;
 } 
 int main (void)
 {
    int hdays, hyears;
    char hmonth[10];
    char *sto [10];
    int ncycle,i;
    scanf("%d",&ncycle);
    for(i=0;i<ncycle;i++)
    {
        scanf("%d.%s%d",&hdays,hmonth,&hyears);
        sto[i]=reverse(hdays, hmonth, hyears);
        printf("%d",i);
     }
     printf("%d\n",ncycle);
     for(i=0;i<ncycle;i++)
     printf("%s",sto[i]);
     return 0; 
 }

Answer 1

char *string;
这里定义了没有分配空间

写成
char *string = (char *)malloc(sizeof(char) * 100);