Fixed random repeatedly in C

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
int makefile(){
    return system("echo %time% > time.txt");
}
void clearchar(char *cha,int len){
    int i;
    for(i=0;i<len;i++){
        if(!('0'<=*(cha+i)&&*(cha+i)<='9'))
            *(cha+i) = '0';
    }
}
int gettime(){
    if(!(makefile())){
        FILE *fp;
        char time[255];
        fp = fopen("time.txt", "r");
        fscanf(fp, "%s", time);
        fclose(fp);
        clearchar(time,strlen(time));
        return atoi(time);

    }else{
        return 0;
    }
}
int main(){
    while(1){
    srand(gettime());
    int r = rand() % 101;
    printf("%d\n",r);
}
}