add inputted filename format checking

src/fileaccess.c

@@ -1,7 +1,22 @@
 #include <stdio.h>
+#include <string.h>
 
-void writeBinaryFile(word instrs[], char outputFile[]){
+bool isValidFileFormat(char filename[], char expectedExtension[]){
+    int *pointLoc = strrchr(filename, '.');
 
+    if(pointLoc != NULL){
+        if(strcmp(pointLoc, expectedExtension)==0){
+            return true;
+        }
+    }
+    return false;
+}
+
+int writeBinaryFile(word instrs[], char outputFile[]){
+
+    if (!isValidFileFormat(filename, "bin")){
+        return(1);
+    }
 
     FILE *fp; 
     
@@ -9,6 +24,9 @@ void writeBinaryFile(word instrs[], char outputFile[]){
     fwrite(instrs, 4, sizeof(instrs), fp);
     fclose(fp);
 
+    return(0);
 }
 
-void readAssemblyFile()
+int readAssemblyFile() {
+
+}