I am trying to write a bunch of files by iterating, doing some calculations and adding the index to the file's name, heres part of my code (I emphasized where the code stops compiling):

```
float AltAzCalc(int d, float t, float Lon, float RA, float Dec, float Lat){
FILE *in;
-----> char filename[30] = ("hiparcos_horizontal_%lf_%lf.csv",Lon,Lat);
in = fopen(filename, "w");
float PI = 3.14159265;// pi
float G = 6.5949997;
float Alt , Az;
float GST = G + 0.0657098244*d + 1.00273791*t;
if (GST > 24){
GST = GST - 24;
}
float LST = GST*360/24 + Lon;
Alt = (180/PI)*(asin(sin(PI*Dec/180)*sin(PI*Lat/180) + cos(PI*Dec/180)*cos(PI*Lat/180)*cos(PI*(LST-RA*360/24)/180)));
if(sin(PI*(LST-RA*360/24)/180) <= 0){
Az = (180/PI)*(acos((sin(PI*Dec/180)-(sin(PI*Alt/180)*sin(PI*Lat/180)))/(cos(PI*Alt/180)*cos(PI*Lat/180))));
}else{
Az = 360 - (180/PI)*(acos((sin(PI*Dec/180)-(sin(PI*Alt/180)*sin(PI*Lat/180)))/(cos(PI*Alt/180)*cos(PI*Lat/180))));
}
fprintf(in," %lf %lf \n",Alt,Az);
}
int main{
for(int i = -180 ; i < 181 ; i++){
for(int j = -180 ; j < 181 ; j++){
for(int k = 0; k < 119616 ; k++){
AltAzCalc(97,9.2,i,AscensionRecta.array[k],Declinacion.array[k],j);
}
}
}
}
```

I get the following Error: ![enter image description here][1]

I have used such syntaxis before only not adding any extra numbers that I want to change, which is a string literal and that's what its asking for, any idea how to fix this?