i want to assign the grades with the grade points how can i do that?

string[] grades = {"A+","A","A-","B+","B","B-","C+","C","C-","D+","D","F"};
float[] gradePoints = { 4.0f,4.0f,3.7f,3.3f,3,2.7f,2.3f,2,1.7f,1.3f,1,0 };

string[] grades = {"A+","A","A-","B+","B","B-","C+","C","C-","D+","D","F"};
float[] gradePoints = { 4.0f,4.0f,3.7f,3.3f,3,2.7f,2.3f,2,1.7f,1.3f,1,0 };