diff --git a/class.c b/class.c
new file mode 100644
index 0000000..7200b69
--- /dev/null
+++ b/class.c
@@ -0,0 +1,96 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void setBit(char *bits, int n)
+{
+    bits[n/8] |= (1 << n%8);
+}
+
+int testBit(char *bits, int n)
+{
+    return bits[n/8] & (1 << n%8);
+}
+
+char *classify(char *spec)
+{
+    char *class= malloc(32);	// 256 bits indicating if character N (bit position N) is in the class or not
+    int index=0;
+    while (spec[index] != '\0' ) {  //*spec
+	// go through spec converting each entry in the spec into a set of bits in the class
+	// test if the next thing is \ .
+	// or test if you have X-Y (where X or Y might be a character or escaped character)
+	//    \n-\r
+       if (spec[index]=='-' && index!=0 && !(index==1 && spec[0]=='^')){
+            if(spec[index+1]=='\0'){
+                printf("Error, bad use of range\n");
+            }
+            if(spec[index-1]<65 || spec[index+1]>122 || (spec[index-1]>90 && spec[index-1]<97) || (spec[index+1]>90 && spec[index+1]<97)){
+                //= if(spec[index-1] or spec[index+1] are not letters)
+
+                if((spec[index-1]>47 && spec[index-1]<57) || (spec[index+1]>47 && spec[index+1]<57) ){ //if it's a digit range
+                    if(spec[index-1]>spec[index+1]){
+                        printf("Error, first digit greater than the second one\n");
+                    }
+                    else{
+                        for(int j=spec[index-1]; j<=spec[index+1] ; j++){
+                            setBit(class,j);
+                            printf("added digit : %c\n",j);
+                        }
+                    }   
+                }
+                else{
+                    printf("Error, aekzaepaz");
+                }
+            }
+            else{
+                if(spec[index-1]>spec[index+1]){
+                printf("Error, first char greater than the second one");
+                }
+                else if(spec[index-1]>=65 && spec[index-1]<=90 && spec[index+1]>=65 && spec[index+1]<=90 ){
+                    for(int j=spec[index-1]; j<=spec[index+1] ; j++){
+                            setBit(class,j);
+                            printf("added char : %c\n",j);
+                    }
+                }
+                else if( spec[index-1]>=97 && spec[index-1]<=122 && spec[index+1]>=97 && spec[index+1]<=122 ){
+                    for(int j=spec[index-1]; j<=spec[index+1] ; j++){
+                            setBit(class,j);
+                            printf("added char : %c\n",j);
+                    }
+                }
+            }
+            
+
+       }
+        printf("%i\n",spec[index]);
+        index++;
+    }
+
+    if (spec[0]=="^") {
+	for (int i= 0;  i < 8;  ++i) class[i] ^= 255;   // invert all bits in the class
+    }
+
+    return class;
+}
+
+int main()
+{
+    char   *line=0;
+    size_t  line_max=0;
+    ssize_t line_len=0;
+    char a='a';
+    printf("%i\n",(int)a);
+    printf("%s",classify("^-abca"));
+    while ((line_len= getline(&line,&line_max,stdin)) >= 0) {
+        if (line_len>0 && line[line_len-1]=='\n') {
+            line[line_len-1]=0;
+        }
+	char *class= classify(line);
+	for (int i= 0;  i < 256;  ++i)
+	    if (testBit(class, i))
+		printf("%02x is set\n", i);
+    }
+
+    return 0;
+}
+