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Lab 1. C Introduction

C: – Developed by Bell lab. in 1972.

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

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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

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Output format:

Mathematic operators: – Similar to those in Matlab

%: Remainder

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Others: – int i=3;

– int a;

If/else:If (condition){ statements;}elseif (condition){ statements;}else{ }

If (condition){ statements;}else{ statements;}

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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}

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Array:

Function:– Call by value

– Call by reference

Elements of the array

Array name

Function name

Return value

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

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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 pointerfp = fopen(“filename.dat","rb");     // rb: read for bitsfor (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,

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File operation (write):

File operations in Matlab:

FILE * fp1;             //declare file pointerfp = fopen(“filename.dat",“wb");     // wb: write for bitsfwrite(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 bitfclose(fid); % float/int32

fid2 = fopen(‘filename.dat','rb','n'); Buffer = fread(fid2,n,'ubit1'); fclose(fid2);                    

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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 s

equence 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.