0_0_18843400_7897.cpp: In function 'int main()': 0_0_18843400_7897.cpp:5:9: error: conflicting declaration 'int t' int t; ^ 0_0_18843400_7897.cpp:4:18: note: previous declaration as 'double t' double a,b,c,t,k,x1,x2,x3,y1,y2,y3,s1,s2; ^