Initial commit

ForNextDay/Lec6/Lec6src/array1.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <stdlib.h>
+#define N 5
+
+int main()
+{
+	int i;
+	int j;
+	int iErr;
+	int a[5];
+
+	printf("i: %p\n",&i);
+	printf("j: %p\n",&j);
+	printf("iErr: %p\n",&iErr);
+	printf("a: %p\n",a);
+
+  printf("enter some integers,followed by ^D on blank line: ");
+	i = 0;
+  iErr = 1;
+	while( iErr != 0 && i < N ){
+		iErr = scanf("%d",&a[i]);
+		i++;
+	}
+
+	for(j = 0; j < i+2; j++)
+		printf("a[%d]: %d @ %p\n", j, a[j], &a[j]);
+
+	return EXIT_SUCCESS;
+}

ForNextDay/Lec6/Lec6src/bigInt.c

@@ -0,0 +1,58 @@
+/* bigInt.c
+ *
+ * Demonstrates use of passing an array to a function.
+ *
+ * Also shows why sizeof() is not a reliable way to discover array size. It
+ *   *only* works correctly inside the function it's declared in. When passed
+ *   to a function, the *address* of teh begining of the array is passed and so
+ *   sizeof() returns the sizeof an address. Here's the compiler output
+ *   (I ignored the compile warnings to run it)
+ *
+ * wightman% gcc bigInt.c
+ * bigInt.c:32:49: warning: sizeof on array function parameter will return size of
+ * 'int *' instead of 'int []' [-Wsizeof-array-argument]
+ * printf("bigInt: sizeof(a): %lu bytes\n", sizeof(arr));
+ *                                                    ^
+ * bigInt.c:29:16: note: declared here
+ * int bigInt(int arr[], int iNarr){
+ *                ^
+ * 1 warning generated.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#define N 5
+
+int bigInt(int arr[], int iNarr);
+
+int main()
+{
+	int i;
+	int iErr;
+	int a[5];
+
+	// sizeof() return a long unsigned int (%lu)
+	printf("main: sizeof(a): %lu bytes\n", sizeof(a));
+
+  printf("enter some integers,followed by ^D on blank line: ");
+	i = 0;
+  iErr = 1;
+	while( iErr != 0 && i < N ){
+		iErr = scanf("%d",&a[i]);
+		i++;
+	}
+
+	printf("Biggest value: %d\n", bigInt(a,N));
+
+	return EXIT_SUCCESS;
+}
+
+int bigInt(int arr[], int iNarr){
+	int i;
+	int big = arr[0];
+	printf("bigInt: sizeof(a): %lu bytes\n", sizeof(arr));
+	for(i=1; i<iNarr; i++){
+		if(arr[i] > big)
+		  big = arr[i];
+	}
+	return big;
+}

ForNextDay/Lec6/Lec6src/decompose.c

@@ -0,0 +1,24 @@
+/* decompose.c
+ *
+ * Demonstrates use of passing and using pointers to/in a function.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+
+void decompose(double x, long* int_part, double* frac_part);
+int main()
+{
+	long i;
+	double d;
+	double pie = 3.14159f;
+	decompose(pie, &i, &d);
+
+	printf("Decomposed values for %lf: %ld, %lf\n", pie, i, d);
+
+	return EXIT_SUCCESS;
+}
+
+void decompose(double x, long* int_part, double*frac_part){
+   *int_part = (long) x;
+   *frac_part = x - *int_part;
+}