(C++) In Logdatei schreiben

#include <math.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <iostream>
#include <time.h>
using namespace std;

/* trainart: 1=GeraderCrunch;2=VarGeraderCrunch;3=TwistedCrunch;4=seitlicherCrunch;5=SeitlicherHaltestütz;6=Rückenübung;7=Liegestütz*/
int trainart = 1;
int trainmany; 
int trainrounds = 1;
int trainstart = 1;
char *trainartt;

void write (){

     FILE *writer;

      char ctrainrounds[10];
      char ctrainmany[10];
     

     writer = fopen("log.txt", "at");
     if ( trainstart == 1 ){
          fputs("\n\n\n---------------------- Next Training ----------------------\n\n",writer);
          trainstart += 1;
          }
     if ( trainart == 1 ) {
          fputs("\n\n-RUNDE- ", writer);
          sprintf(ctrainrounds, "%d", trainrounds);
          fputs(ctrainrounds, writer);
          }
          
          

     fputs(trainartt, writer);
     sprintf(ctrainmany, "%d%", trainmany);
     fputs(ctrainmany, writer);

     fclose(writer);
     
     
     }
     

int main (){

int again = 1;
clock_t start,wait;



printf("\nViel Spass beim Ueben!\n\n");
printf("Fangen wir an!\n\n");

do {
    if ( trainrounds == 1) {
         printf("Zum Aufwärmen nicht so viele!\n\n\n");
         }
    else {
         printf("Weiter!!! \a\a\a\a\a\a\a \n\n");
         printf("Runde %d!\n\n\n",trainrounds);
         }
    do {
    
    switch (trainart) {
     case 1: trainartt = "\n\n\nGerader Crunch:\t";
             break;
     case 2: trainartt = "\n\nVariation des Geraden Crunches:\t";
             break;   
     case 3: trainartt = "\n\nTwisted Crunch:\t";
             break;
     case 4: trainartt = "\n\nSeitlicher Crunch:\t";
             break;
     case 5: trainartt = "\n\nSeitlicher Haltestütz:\t";
             break;
     case 6: trainartt = "\n\nRückenuebung:\t";
             break;
     case 7: trainartt = "\n\nLiegestütz:\t";
             break;
             }
     
    printf("%s",trainartt);
    cin >> trainmany;
    write();
    trainart +=1;
    } while ( trainart !=8 );
    
    
    
    
    trainrounds += 1;
    trainart=1;
    printf("\n\nSchon schlappmachen?");
    cin >> again;
    
    printf("\n\n2 Minuten Pause!\n\n");
    wait=120*CLOCKS_PER_SEC;
    start=clock();
    while(clock() < start+wait) {};
    
} while(again == 1);

}