File manipulation in C

#include
#include

int main()
{
FILE *fp;
int returnvar = 1;
char ans = 'y';
char filename[20];
char statement[30];
while(returnvar!=0)
{
printf("enter filename: ");
scanf("%s",filename);
printf("\nWriting to %s...\n\n",filename);
if((fp=fopen(filename,"r"))!=NULL)
{
printf("error: file already exists\n");
returnvar = 1;
exit(1);
}
else
{
if((fp=fopen(filename,"w+"))==NULL)
{
printf("error creating file\n");
returnvar = 1;
exit(1);
}
else
{
printf("writing successful\n");
break;
}
}
}
while(ans!='n')
{
printf("enter a statement to write to file of not more than 30 characters");
scanf("%s",statement);
fprintf(fp,statement);
fprintf(fp,"\n");
printf("input another statement? ");
scanf("%c",&ans);
}
fclose(fp);
return 0;
}