diff --git a/3rd Sem (Data Structure)/array.c b/3rd Sem (Data Structure)/array.c
new file mode 100644
index 0000000..b22de75
--- /dev/null
+++ b/3rd Sem (Data Structure)/array.c	
@@ -0,0 +1,121 @@
+#include<stdio.h>
+#include<conio.h>
+struct Student
+{
+char name[25];
+ int usn;
+ int m1,m2,m3;
+};
+char filename[15];
+int n;
+struct Student s;
+void Insert()
+{
+FILE *fp;
+int i;
+printf("\n\n\tEnter how many Records: ");
+scanf("%d",&n);
+fp=fopen(filename,"w");
+if(fp==NULL) printf("\n\n\tError in Creating the File....");
+else
+for(i=0;i<n;i++)
+{
+ printf("\nEnter Details of Student-%d: ",i+1);
+ printf("\n\t\t\tName: "); scanf("%s",s.name); fprintf(fp,"%s
+",s.name);
+ printf("\n\t\t\tUsn : "); scanf("%d",&s.usn); fprintf(fp,"%d
+",s.usn);
+ printf("\n\t\t\tM1 : "); scanf("%d",&s.m1); fprintf(fp,"%d ",s.m1);
+ printf("\n\t\t\tM2 : "); scanf("%d",&s.m2); fprintf(fp,"%d ",s.m2);
+ printf("\n\t\t\tM3 : "); scanf("%d",&s.m3); fprintf(fp,"%d ",s.m3);
+ }
+ fclose(fp);
+}
+void Search()
+{
+if(n==0)
+printf("\n\n\tNo Records to Search...");
+ else
+ {
+ FILE *fp;
+ int i,flag=0,usn;
+ fp=fopen(filename,"r");
+if(fp==NULL)
+printf("\n\n\tERROR!! in Opening the File....");
+else
+ {
+printf("\n\n\tEnter the Usn to be Searched: ");
+scanf("%d",&usn);
+for(i=0;i<n;i++)
+{
+fscanf(fp,"%s",s.name);
+fscanf(fp,"%d",&s.usn);
+fscanf(fp,"%d",&s.m1);
+fscanf(fp,"%d",&s.m2);
+fscanf(fp,"%d",&s.m3);
+if(usn==s.usn)
+{
+ flag=1;
+ break;
+}
+ }
+ if(flag==1)
+ {
+ printf("\nRecord Exist And Details are:");
+ printf("\n\t\t\t\tName: %s",s.name);
+ printf("\n\t\t\t\tUsn : %d",s.usn);
+ printf("\n\t\t\t\tM1 : %d",s.m1);
+ printf("\n\t\t\t\tM2 : %d",s.m2);
+  printf("\n\t\t\t\tM3 : %d",s.m3);
+ }
+ else
+ printf("\n\n\tRecord having Usn %d Does Not
+Exist...\n\n",usn);
+ }
+ fclose(fp);
+ }
+}
+void Display()
+{
+if(n==0)
+printf("\n\n\tNo Records to Display....\n\n");
+else
+ {
+ int i;
+ FILE *fp=fopen(filename,"r");
+ if(fp==NULL)
+printf("\n\n\tERROR!! in Opening File...");
+ else
+for(i=0;i<n;i++)
+ {
+printf("\nDetails of Student-%d: ",i+1);
+fscanf(fp,"%s",s.name); printf("\n\t\t\tName: %s",s.name);
+fscanf(fp,"%d",&s.usn); printf("\n\t\t\tUsn : %d",s.usn);
+fscanf(fp,"%d",&s.m1); printf("\n\t\t\tM1 : %d",s.m1);
+fscanf(fp,"%d",&s.m2); printf("\n\t\t\tM2 : %d",s.m2);
+fscanf(fp,"%d",&s.m3); printf("\n\t\t\tM3 : %d",s.m3);
+ }
+ fclose(fp);
+ }
+}
+void main()
+{
+int ch;
+clrscr();
+printf("\n\n\tEnter the File Name: ");
+scanf("%s",filename);
+while(1)
+{
+printf("\n\n\t1.Insert...\t2.Search...\t3.display...\t4.Exit...");
+ printf("\n\n\tEnter Your Choice: ");
+ scanf("%d",&ch);
+ switch(ch)
+ {
+ case 1: Insert(); break;
+ case 2: Search(); break;
+ case 3: Display(); break;
+ case 4: exit(0);
+ default: printf("\n\n\tEnter Proper Choice...");
+ }
+ }
+}  
diff --git a/st2.c b/st2.c
new file mode 100644
index 0000000..57c463f
--- /dev/null
+++ b/st2.c
@@ -0,0 +1,50 @@
+#include<stdio.h>
+int main()
+{
+intlocks,stocks,barrels,sales,flag=0;
+float commission;
+printf("Enter the total number of locks\n");
+scanf("%d",&locks);
+printf("Enter the total number of stocks\n");
+scanf("%d",&stocks);
+printf("Enter the total number of barrels\n");
+scanf("%d",&barrels);
+if((locks<=0) || (locks>70))
+{
+flag=1;
+printf("Locks Out of Range\n");
+}
+if((stocks<=0) || (stocks>80))
+{
+flag=1;
+printf("Stocks Out of Range\n");
+}
+if((barrels<=0) || (barrels>90))
+{
+flag=1;
+printf("Barrels Out of Range\n");
+}
+if(flag == 1)
+{
+printf("Invalid input\n");
+return 0;
+}
+sales= locks*45 + stocks*30 + barrels*25;
+if(sales <= 1000)
+{
+commission = 0.10 * sales;
+}
+else if(sales <= 1800)
+{
+commission = 0.10 * 1000;
+commission = commission + (0.15 * (sales - 1000));
+}
+else
+{
+commission = 0.10 * 1000;
+commission = commission + (0.15 * 800);
+commission = commission + (0.20 * (sales - 1800));
+}
+printf("Total sales: %d and Commission: %f\n",sales,commission);
+return 0;
+}