diff --git a/Appendix1/Assertion/Assertions.c b/Appendix1/Assertion/Assertions.c
new file mode 100644
index 0000000..40a0388
--- /dev/null
+++ b/Appendix1/Assertion/Assertions.c
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <assert.h>
+
+int main()
+{
+    int x = 7;
+
+    /*  Some big code in between and let's say x
+       is accidentally changed to 9  */
+    x = 9;
+
+    // Programmer assumes x to be 7 in rest of the code
+    assert(x==7);
+
+    /* Rest of the code */
+
+    return 0;
+}
\ No newline at end of file
diff --git a/Appendix1/CodeBlocking/Blocking.c b/Appendix1/CodeBlocking/Blocking.c
new file mode 100644
index 0000000..ac55f27
--- /dev/null
+++ b/Appendix1/CodeBlocking/Blocking.c
@@ -0,0 +1,45 @@
+#include<stdio.h> 
+
+#define BLOCKSIZE (8) 
+
+int main(void)
+{ 
+    int i = 0; 
+    int limit = 19;  /* could be anything */ 
+    int blocklimit; 
+
+    /* The limit may not be divisible by BLOCKSIZE, 
+    * go as near as we can first, then tidy up.
+    */ 
+    blocklimit = (limit / BLOCKSIZE) * BLOCKSIZE; 
+    /* unroll the loop in blocks of 8 */ 
+    while( i < blocklimit ) 
+    { 
+        printf("process(%d)\n", i); 
+        printf("process(%d)\n", i+1); 
+        printf("process(%d)\n", i+2); 
+        printf("process(%d)\n", i+3); 
+        printf("process(%d)\n", i+4); 
+        printf("process(%d)\n", i+5); 
+        printf("process(%d)\n", i+6); 
+        printf("process(%d)\n", i+7); 
+
+        /* update the counter */ 
+        i += 8; 
+    }
+    if( i < limit ) 
+    { 
+        /* Jump into the case at the place that will allow
+        * us to finish off the appropriate number of items. */
+        switch( limit - i ) 
+        { 
+            case 7 : printf("process(%d)\n", i); i++; 
+            case 6 : printf("process(%d)\n", i); i++; 
+            case 5 : printf("process(%d)\n", i); i++; 
+            case 4 : printf("process(%d)\n", i); i++; 
+            case 3 : printf("process(%d)\n", i); i++; 
+            case 2 : printf("process(%d)\n", i); i++; 
+            case 1 : printf("process(%d)\n", i); 
+        }
+    } 
+}
\ No newline at end of file
diff --git a/Appendix1/DebugAssertion/DebugAssertion.c b/Appendix1/DebugAssertion/DebugAssertion.c
new file mode 100644
index 0000000..6f7c59c
--- /dev/null
+++ b/Appendix1/DebugAssertion/DebugAssertion.c
@@ -0,0 +1,11 @@
+# define NDEBUG
+#include <stdio.h>
+# include <assert.h>
+
+int main()
+{
+    int x = 7;
+    assert (x==5);
+    printf("x = %d\n", x);
+    return 0;
+}
\ No newline at end of file
diff --git a/LC21/cond.c b/LC21/Cond/cond.c
similarity index 100%
rename from LC21/cond.c
rename to LC21/Cond/cond.c