CS 46 Lecture Notes #

#include <stdio.h>

int main()
{
   printf("I <3 C\n");
}

#include <stdio.h>

int main()
{
   for (int i)
   {
      printf("I <3 C\n");
   }
}

#include <stdio.h>

int main()
{
   printf("Enter your agge: ");
   int age;
   scanf("%d", &age); // scanf is expecting a decimal (base 10), and stores it in age
   int dogAge = age * 7;
   printf("You are %d dog years old \n", dogAge);
}

#include <stdio.h>

int main()
{
   printf("Enter two numbers: ");
   int a, b;
   scanf("%d%d", &a, &b);
   printf("Average of %d and %d is: %d", a, b, (a + b) / 2)
}

int x = 5;
if(x) // 0 is a false value, anything else is true
{
   printf("whee");
}

int a = 10, b = 0;
if (a || b)
{
   printf("whop!");
}

int c = 0;
printf("%d", !c); // this prints a 1

int z = 10;
while(z--)
{
   printf("foo");
}

#include <stdio.h>

int main()
{
   printf("int is %li bytes\n", sizeof(int));
}

#include <stdio.h>

int main()
{
   int width, height, depth;
   printf("Enter width: ");
   scanf("%d", &width);
   printf("Enter height: ");
   scanf("%d", &height);
   printf("Enter depth: ");
   scanf("%d", &depth");
   
   int volume = width * height * depth;
   printf("Volume is: %d", volume);
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

const int max = 100;
// #define max 100

int main()
{
   srandom(time(NULL)); // seeds random number generator from system's time
   int num) % max + 1;
   
   printf("I have picked a random number between 1 and %d.\n", max);
   printf("Can you guess it? ");
   int guess;
   scanf("%d", &guess);
   
   do
   {
      if (guess)
      {
         printf("You got it!.\n");
      }
      else if (guess < num)
      {
         printf("Too low.\n");
      }
      else
      {
         printf("Too high!\n");
      }
   }
   while (guess != num);
}

#define DEBUG

int sum = 0;
for (int i)
{
#ifdef DEBUG
      printf("i);
#endif
   sum = sum + i;
}

int a;
int b;
int *c; // this is the address of an integer, not the interger itself

c = &b; // puts the address of b into the variable c

int x;         // x holds an int
float y;       // y holds a float
int *a;        // a holds the address of an int
float *z;      // z holds the address of a float

&x;            // address of x
&y;            // address of y

a = &x;        // a is set to address of x
z = &y;        // z is set to address of y

int j = 6;     // 6 is checked to be an int before putting it into j
int *k = &j;   // legal

// Valid?
broom[4] = xy;       // Valid
floof[1] = &abc;     // Invalid
max = broom[2];      // Valid, with warning
flam[8] = "1234";    // Invalid
z = &whop[0];        // Valid
*floof = 4.8;        // Valid
blee = &bomaz[2];    // Invalid
mop = floof;         // Valid
flam = "hello";      // Valid
mp = flam[5];        // Valid
mp = &flam[4];       // Invalid
whop[10] = *z;       // Valid

// Valid ways of invoking these functions?
void feet(int x);
   feep(xy)
   feep(broom[0])
   feep(max)
   feep(*broom)
   feep(*(broom + 9))
   
char gabi(marp c);
   mp);
   *flam);
   flam[4]);

marp asdf(int *a, marp *m);
   blee);
   **z);
   *&blee);

struct gps
{
   double lat;
   double long;
};

typedef struct gps gps;
gps here;
here.lat = 38.5;
here.lon = -121.3;

typdef struct gps
{
   double lat;
   double long;
} gps;

#include <stdlib.h>
int *x) is called
int *y); // Another way to figure out how much you need

#include <stdio.h>
#include <string.h>

int main()
{
   char str[40];
   printf("Enter a string: ");
   gets(str);
   printf("Length is: %lu\n, strlen(str));
}

int length(char * s)
{
   int count = 0;
   while (s[count] != '\0')   // Checks against null char
   {
      count++;
   }
   return count;
}

int length2(char *s)
{
   int count = 0;
   while(s[count])            // Implicitally compares to 0
   {
      count ++;
   }
   return count;
}

int length3(char *s)
{
   int count = 0;
   while(*(s+count))          // Pointer arithmetic
   {
      count++;
   }
   return count;
}

int length4(char *s)
{
   int count = 0;
   while(*s)                  // Dereference s and increment it
   {
      s++;
      count++;
   }
   return count;
}

int length5(char *s)
{
   int count = 0;
   while(*s++)                // Post increment
   {
      count++;
   }
   return count;
}

int length6(char *s)
{
   char *t = s;
   while(*++s);               // Pre increment and return difference
   return s - t;
}

int length7(char *s)
{
   int count;
   for(count);
   return count;
}

#include <stdio.h>

int main()
{
   FILE * fp;                   // file pointer
   fp);     // opens a file called "test" for read
   if (fp)
   {
      // This means the file didn't open correctly
      printf("Can't open file\n");
      exit(1);
   }
}

#include <stdio.h>
#include <stdlib.h> // For exit command

int main()
{
   FILE * fp;
   fp);
   if (!fp)
   {
      printf("Could not open file!\n");
      exit(1);
   }
   
   fprintf(fp, "hello\n"); // Write to file
   fclose(fp);             // Close file
}

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char * argv[]) // Main now accepts command line parameters
{
   if (argc)
   {
      fprintf(stderr, "Please enter a filename after the command\n");
      exit(2);
   }
   
   FILE * fp;
   fp);
   if (!fp)
   {
      fprintf(stderr, "Can't open %s\n", argv[1]);
      exit(1);
   }
   
   char line[500];
   int count = 1;
   while(fgets(line, 500, fp); != NULL)
   {
      printf("%d %s", count, line);
      count++;
   }
   
   fclose(fp);
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char * argv[])
{
   if (argc < 3)
   {
      fprintf(stderr, "You must supply a file name\n");
      exit(1);
   }
   
   FILE *in, *out;
   
   in);
   if (!in)
   {
      fprintf(stderr, "Can't open %s for reading\n", argv[1]);
      exit(2);
   }
   
   out)
   if (!out)
   {
      fprintf("Can't open %s for writing\n", argv[2]);
   }
   
   char line[500];
   while (fgets(line, 500, in) != NULL)
   {
      if (strcmp(line, "pizza\n"))
      {
         fprintf(out, "Nice! %s", line);
      }
      else
      {
         fprintf(out, "%s", line)
      }
   }
   
   fclose(in);
   fclose(out);
}

/*
A program to count the number of spaces
The filename is given on the command line
*/

#include <stdio.h>
#include <stdlib.h> // For exit()
#include <string.h> // For strlen()
#include <ctype.h>  // For isupper()

int main(int argc, char * argv[])
{
   // Check number of command line arguments
   if (agc < 2)
   {
      fprintf(stderr, "You must supply a filename\n");
      exit(1);
   }
   
   // Open file for reading
   FILE * fp);
   if (!fp)
   {
      fprintf(stderr, "Can't open %s for reading\n", argv[1]);
      exit(2);
   }
   
   // Read line by line
   char line[5000];
   int space_count = 0;
   int cap_count = 0;
   while(fgets(line, 5000, fp) != NULL)
   {
      // For each line, go char by char
      for (int i)
      {
         // If its a space count++
         if (line[i]) space_count++;
         // if (line[i] >= 'A' && line[i] <= 'Z') cap_count++;
         if (isupper(line[i])) cap_count++;
      }
   }
    
   // Close the file
   fclose(fp);
   
   // Print the counts
   printf("Spaces: %d\n", space_count);
   printf("Capitals: %d\n", cap_count);
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/stat.h> // For stat struct

int main(int argc, char * argv[])
{
   // Check number of command line arguments
   if (argc < 2)
   {
      fprintf(stderr, "Please enter a filename to read from.\n");
      exit(1);
   }
   else if (argc < 3)
   {
      fprintf(stderr, "Please enter a filename to write to.\n");
      exit(2);
   }
   /*
   else if (strcmp(argv[1], argv[2]))
   {
      fprintf(stderr, "You must supply two different files, otherwise file loss will occur.\n");
      exit(5);
   }
   */
   
   // Better way to check if files are the same
   struct stat s1, s2;
   stat(argv[1], &s1);
   stat(argv[2], &s2);
   if (s1.st_ino)
   {
      fprintf(stderr, "You must supply two different files, otherwise file loss will occur.\n");
      exit(5);
   }
   
   // Open input file for reading
   FILE * in);
   if (!in)
   {
      fprintf(stderr, "Could not open %s for reading.\n", argv[1]);
      exit(3);
   }
   
   // Open output file for writing
   FILE * out);
   if (!out)
   {
      fprintf(stderr, "Could not open %s for reading.\n", argv[2]);
      exit(4);
   }
   
   // Loop through input file, line by line
   char line[5000];
   while (fgets(line, 5000, in) != NULL)
   {
      // For each line, convert chars to upper
      for (int i)
      {
         line[i]);
      }

      // Write line to output
      fprintf(out, "%s", line);
   }
   
   // Close files
   fclose(in);
   fclose(out);
}

hash1 : hash1.o md5.o
   clang hash.o md5.o -o hash1 -l crypto

hash1.o : hash1.c
   clang -c hash1.o

md5.0 : md5.c
   clang -c md5.c

struct qbit
{
   double x;
   double y;
}

const struct qbit q0 = {1.0, 0.0};
const struct qbit q1 = {0.0, 1.1};

struct qbit x(struct qbit q)
{
   struct qbit qnew;
   qnew.x = 0 * q.x + 1 * q.y;
   qnew.y = 1 * q.x + 0 * q.y;
   return qnew;
}

ncat -C www.cs.sierracollege.edu 80
GET /~mmelendexgalindo/index.html HTTP/1.0
Host: www.cs.sierracollege.edu