1 Lab 1. C Introduction  C: –Developed by Bell lab. in –a procedure-oriented programming language.  Developing environments: –Editing –Preprocessing (header files) –Compile (.obj) –Link (.exe) –load –Execution  Include: –Head files used in the main file. #include

2  Variable and constant: –Must be declared before use –e.g. int i=3; float f=15.7; double x. –const int max=100;  Data type transfer: –Assignment: x=1; –Mathematic operations: y=i/5+2/3; –Model transfer: i=(int)(x+0.5); –Function call: x=sum(a,b);  Basic input/output commands: printf(“\t xxxx %vf1 xxx %vf2 xxx \n”, var1, var2); scanf(“\t %vf1 %vf2 ”, &var1, &var2); Variable format Address

3  Output format:  Mathematic operators: –Similar to those in Matlab %: Remainder

4  Others: –int i=3; –int a;  If/else: If (condition) { statements; } elseif (condition) { statements; } else { } If (condition) { statements; } else { statements; }

5  Practice 1: –Input three numbers from the keyboard. –Calculate the maximum, the minimum, and the average values. –Print the result on the screen.  For loops: for (initial setting; terminate conditions; index operations) { statements }

6  Array:  Function: –Call by value –Call by reference Elements of the array Array name Function name Return value

7  Define (preprocessor): –Increase readability –Increase the flexibility for paramter changes –Replace simple function

8  Practice 2: –Input two sequences from the keyboard. –Calculate the convolution of the sequences. –Print the result on the screen.  File operations (read): FILE * fp; //declare file pointer fp = fopen(“filename.dat","rb"); // rb: read for bits for (i=0 ; i<512 ; i++) { fread(&temp,1,4,fp); // 1: one byte, 4: 4x1 bytes at a time x[i] = temp; // store the read value into an array } * int/float: use 4 bytes to store one value FILE * fp; fp = fopen(“filename.dat","rb"); fread(x,4,sizeof(x),fp); Or,

9  File operation (write):  File operations in Matlab: FILE * fp1; //declare file pointer fp = fopen(“filename.dat",“wb"); // wb: write for bits fwrite(x,4,sizeof(x),fp1); // 4: 4 bytes a unit r = randint(1,n); s = r > 0.5; fid = fopen(‘filename.dat','wb'); fwrite(fid, s,'ubit1'); % ubit1: unsigned bit fclose(fid); % float/int32 fid2 = fopen(‘filename.dat','rb','n'); Buffer = fread(fid2,n,'ubit1'); fclose(fid2);

10  Practice 3: –Store the values of inputted two sequences in two files. –Read the values from the files. –Calculate the convolution of the sequences. –Store the result into another file.  Homework –Find out how to create a function with sequence input and sequence output. –Rewrite the convolution operations with a function. –Generate two sequences with Matlab and store them in the two files. –Use C to read the files and conduct convolution operations. –Store the result to another file and use Matlab to read it.