diff --git a/C18/ex2.c b/C18/ex2.c
new file mode 100644
index 0000000..1217fe9
--- /dev/null
+++ b/C18/ex2.c
@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+// Main () - execution starts here
+int main (void)
+{
+    // Declate file stream variables
+    FILE *fInput, *fOutput;
+
+    // Other variables needed
+    int i, d, d2;
+
+    // Try and open the text "sample.txt" (in the current directory) file for writing
+    fOutput = fopen ("numbers.txt", "w");
+
+    // Check we were able to open the file
+    if ( fOutput == NULL)
+    {
+        printf ("The file could not be opened for writing, exiting\n");
+        return -1;
+    }
+
+    // Use a loop to write values to the newly created file
+    for ( i = 1 ; i <= 10 ; i++)
+    {
+        fprintf (fOutput, "%d %d\n", i, i*i);
+    }
+
+    // And close the file
+    fclose (fOutput);
+
+    // Try and open the binary "numbers " (in the current directory) file for reading
+
+    fInput = fopen ("numbers.txt", "r");
+
+    // Check we were able to open the file
+    if ( fInput == NULL)
+    {
+        printf ("The file could not be opened for reading, exiting\n");
+        return -1;
+    }
+ 
+    // Read, line by line the 10 values written into variable d
+    // and then display the contents of d on the screen
+    for ( i = 1 ; i <= 10 ; i++)
+    {
+        fscanf (fInput, "%d %d", &d, &d2);
+        printf ("Value read from file: %d %d\n", d, d2);
+    }
+
+    // And close the file
+    fclose (fInput);
+
+    return (0);     // Exit indicating success
+}
diff --git a/C18/ex3.c b/C18/ex3.c
new file mode 100644
index 0000000..2b8dec4
--- /dev/null
+++ b/C18/ex3.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+// Main () - execution starts here
+int main (void)
+{
+    // Declate file stream variables
+    FILE *fInput, *fOutput;
+    // 8x the maximum filename length on most filesystems should be a decent size
+    char filename[2049] = { 0 };
+
+    printf("Enter filename: ");
+    scanf("%2048s", filename);
+
+    // Other variables needed
+    int i, d, d2;
+
+    // Try and open the text "sample.txt" (in the current directory) file for writing
+    fOutput = fopen (filename, "w");
+
+    // Check we were able to open the file
+    if ( fOutput == NULL)
+    {
+        printf ("The file could not be opened for writing, exiting\n");
+        return -1;
+    }
+
+    // Use a loop to write values to the newly created file
+    for ( i = 1 ; i <= 10 ; i++)
+    {
+        fprintf (fOutput, "%d %d\n", i, i*i);
+    }
+
+    // And close the file
+    fclose (fOutput);
+
+    // Try and open the binary "numbers " (in the current directory) file for reading
+
+    fInput = fopen ("numbers.txt", "r");
+
+    // Check we were able to open the file
+    if ( fInput == NULL)
+    {
+        printf ("The file could not be opened for reading, exiting\n");
+        return -1;
+    }
+ 
+    // Read, line by line the 10 values written into variable d
+    // and then display the contents of d on the screen
+    for ( i = 1 ; i <= 10 ; i++)
+    {
+        fscanf (fInput, "%d %d", &d, &d2);
+        printf ("Value read from file: %d %d\n", d, d2);
+    }
+
+    // And close the file
+    fclose (fInput);
+
+    return (0);     // Exit indicating success
+}
diff --git a/C18/ex4.c b/C18/ex4.c
new file mode 100644
index 0000000..42aaf52
--- /dev/null
+++ b/C18/ex4.c
@@ -0,0 +1,92 @@
+#include <stdio.h>
+#include <math.h>
+#include <stdlib.h>
+
+
+float degrees_to_radians(float degrees) {
+	return M_PI * degrees / 180.0;
+}
+
+
+// Simple function to populate an integer array
+void PopulateTheArray ( int Size, float ArrayData[])
+{
+    int i;      // Variable to use in our loop
+
+    for ( i = 0 ; i < Size ; i++)
+    {
+        ArrayData[i] = degrees_to_radians(i); // Treat it like a normal array
+    }
+}
+// Simple function do display contents an integer array
+void DisplayTheArray ( int Size, float ArrayData[])
+{
+    int i;      // Variable to use in our loop
+
+    for ( i = 0 ; i < Size ; i++)
+    {
+        printf ("%d\t%0.3f\n", i, ArrayData[i]);
+    }
+}
+
+int SaveArray (char *filename, int Size, float ArrayData[])
+{
+	FILE *fp;   // File Pointer
+	int i;      // Variable to use in our loop
+
+	fp = fopen(filename, "w");
+	// if file open failed, return error to caller
+	if (fp == NULL) {
+		return 1;
+	}
+
+
+	for ( i = 0 ; i < Size ; i++)
+	{
+		fprintf(fp, "%d\t%0.3f\n", i, ArrayData[i]);
+	}
+
+	// close file, returns 0 on successful closing (therefore function has executed sucessfully)
+	return fclose(fp);
+}
+// Main () - execution starts here
+int main (void)
+{
+    char filename[2049];
+    int rc, iSizeForArray;
+    float *pData;              // A pointer to hold the base address of out array
+
+    // Ask for the size of the array and store result
+
+    printf("Please enter the size of the array to dynamically allocate: ");
+    scanf ("%d", &iSizeForArray);
+
+    // Use calloc with checking
+    pData = calloc( iSizeForArray, sizeof (float));
+
+    // Check we got the memory
+    if ( pData == NULL)
+    {
+        printf ("Sorry, I could not allocate the memory, bye!\n");
+        return -1;
+    }
+
+    // Pass the size, iSizeForArray) and the pointer created 
+    // which points to the start of the sucesfully allocated memory
+
+    PopulateTheArray(iSizeForArray, pData);
+    DisplayTheArray(iSizeForArray, pData);
+
+    // Exercise doesn't ask to use function but kind of pointless without
+    printf("Enter filename: ");
+    scanf("%2048s", filename);
+    rc = SaveArray(filename, iSizeForArray, pData);
+    if (rc != 0) {
+	    printf("Error saving file\n");
+	    free(pData);
+	    return rc;
+    }
+
+    free(pData);	    // Free up the memory before exiting
+    return (0);     // Exit indicating sucess
+}
diff --git a/C18/ex5.c b/C18/ex5.c
new file mode 100644
index 0000000..a5a8136
--- /dev/null
+++ b/C18/ex5.c
@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <math.h>
+#include <stdlib.h>
+
+
+float degrees_to_radians(float degrees) {
+	return M_PI * degrees / 180.0;
+}
+
+
+// Simple function to populate an integer array
+void PopulateTheArray ( int Size, float ArrayData[])
+{
+    int i;      // Variable to use in our loop
+
+    for ( i = 0 ; i < Size ; i++)
+    {
+        ArrayData[i] = degrees_to_radians(i); // Treat it like a normal array
+    }
+}
+// Simple function do display contents an integer array
+void DisplayTheArray ( int Size, float ArrayData[])
+{
+    int i;      // Variable to use in our loop
+
+    for ( i = 0 ; i < Size ; i++)
+    {
+        printf ("%d\t%0.3f\n", i, ArrayData[i]);
+    }
+}
+
+int SaveArrayBinary (char *filename, int Size, float ArrayData[])
+{
+	FILE *fp;   // File Pointer
+	int i;      // Variable to use in our loop
+
+	fp = fopen(filename, "wb");
+	// if file open failed, return error to caller
+	if (fp == NULL) {
+		return 1;
+	}
+
+	// write data
+	fwrite(ArrayData, sizeof(float), Size, fp);
+	// close file, returns 0 on successful closing (therefore function has executed sucessfully)
+	return fclose(fp);
+}
+// Main () - execution starts here
+int main (void)
+{
+	char filename[2049];
+	int rc, iSizeForArray;
+	float *pData;              // A pointer to hold the base address of out array
+
+	// Ask for the size of the array and store result
+
+	printf("Please enter the size of the array to dynamically allocate: ");
+	scanf ("%d", &iSizeForArray);
+
+	// Use calloc with checking
+	pData = calloc( iSizeForArray, sizeof (float));
+
+	// Check we got the memory
+	if ( pData == NULL)
+	{
+		printf ("Sorry, I could not allocate the memory, bye!\n");
+		return -1;
+	}
+
+	// Pass the size, iSizeForArray) and the pointer created 
+	// which points to the start of the sucesfully allocated memory
+
+	PopulateTheArray(iSizeForArray, pData);
+	DisplayTheArray(iSizeForArray, pData);
+
+	// Exercise doesn't ask to use function but kind of pointless without
+	printf("Enter filename: ");
+	scanf("%2048s", filename);
+	rc = SaveArrayBinary(filename, iSizeForArray, pData);
+	if (rc != 0) {
+		printf("Error saving file\n");
+		free(pData);
+		return rc;
+	}
+
+	free(pData);    // Free up the memory before exiting
+	return (0);     // Exit indicating sucess
+}
diff --git a/C18/ex6.c b/C18/ex6.c
new file mode 100644
index 0000000..f315699
--- /dev/null
+++ b/C18/ex6.c
@@ -0,0 +1,51 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+int main() {
+	FILE *fp;                    // file pointer
+	float *data;                 // data pointer (array of floats)
+	int i, file_size, arr_size;
+	char filename[2049];
+
+	printf("Enter filename to read: ");
+	scanf("%2048s", filename);
+
+	fp = fopen(filename, "rb");
+	if (fp == NULL) {
+		printf("Failed to open file\n");
+		return 1;
+	}
+
+	// get file size (technically isn't the best way because SEEK_END is undefined behaviour:
+	//
+	// "Library implementations are allowed to not meaningfully support SEEK_END
+	// (therefore, code using it has no real standard portability)."
+	// ~ https://cplusplus.com/reference/cstdio/fseek/
+	//
+	// " Setting the file position indicator to end-of-file, as with fseek(file, 0, SEEK_END),
+	// has undefined behavior for a binary stream (because of possible trailing null characters) or
+	// for any stream with state-dependent encoding that does not assuredly end in the initial shift
+	// state. "
+	// ~ https://port70.net/~nsz/c/c11/n1570.html#note268
+	//
+	// it is also limited to 2GB files as it returns a signed integer
+	// better to use something like this probably:
+	// https://stackoverflow.com/a/238609
+	//
+	// but louise uses fseek so i will too
+	fseek(fp, 0, SEEK_END);
+	file_size = ftell(fp);
+	arr_size = file_size/sizeof(float);
+	rewind(fp);
+
+	// allocate memory and read data
+	data = malloc(file_size);
+	fread(data, sizeof(float), arr_size, fp);
+
+	for (i = 0; i < arr_size; i++) {
+		printf("%d %0.3f\n", i, data[i]);
+	}
+
+	free(data);
+}