ES101 - Lesson 9 : Structures - Revision history

Preet: /* Assignment */

2013-10-15T19:32:06Z

‎Assignment

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‎Passing structure to a function

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‎Passing structure to a function

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‎Declare and use structure

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‎Type Define Structure

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2013-07-30T21:19:34Z

‎Passing structure to a function

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‎Passing structure to a function

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‎Type Define Structure

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 #*:  Declares a single student, uses printf()/scanf() to get input
 #*:  Returns the single student back
-#*  '''<code>printStudentInfo(student_t st_ptr)</code>'''
+#*  '''<code>printStudentInfo(student_t *st_ptr)</code>'''
 #*:  Takes the pointer to a student (to avoid making a copy)
 #*:  Prints out all of the student information

@@ Line 105: / Line 105: @@
 <BR/>
-Now, let's do the same thing, but this time, using a pointer to populate student structure:
+In this example, we use a pointer to the structure.  Unlike a pointer to a variable, we have to access the members of the structure using the '''<code> -> </code>''' operator.  This operator means "pointer to the member" of the structure.  It is similar to using the dot operator.  If we had used a non-pointer version and the dot operator, it would've only modified the "copy of the structure" rather than the "memory of the structure".
 <syntaxhighlight lang="c">
 #include <stdio.h>
 typedef struct {
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 } student_t;
 void get_student_info(student_t *student);

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 Structure(s) can be passed to a function just like a variable.  It is recommended that you pass a pointer instead of a copy because passing a very large structure to a function as a copy can consume a lot of memory.
-Let's demonstrate both uses :
+In the example below, we have a function that populates a single student information, and then return it.  In the <code>main()</code> function, we then use this function to capture the returned structure into the array.  This demonstrates one way to populate the student array, which "returns" the entire structure back that is copied (less efficient) into the array.
 <syntaxhighlight lang="c">
 #include <stdio.h>

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 </syntaxhighlight>
 <BR/>
 == Passing structure to a function ==
 Structure(s) can be passed to a function just like a variable.  It is recommended that you pass a pointer instead of a copy because passing a very large structure to a function as a copy can consume a lot of memory.

← Older revision		Revision as of 19:25, 15 October 2013
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	</syntaxhighlight>		</syntaxhighlight>

		+	Structure is declared using <code>typedef struct</code>. You enclose the "members" inside the curly braces. These members are then accessed using the '''dot operator''' as demonstrated below. The name of the structure, or "your variable type" appears after the closing } curly brace.
	<BR/>		<BR/>

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 Structures can help you group information together.  For example, if you wish to ask for student age, ID, and name, you can group this data into a single structure that represents one student.
-Video Demonstrates :
+Video Demonstration :
-*  <Coming soon>
+*  [http://www.youtube.com/watch?v=5FDydQd2SOo C/C++ Structures]
 == Type Define Structure ==
@@ Line 145: / Line 145: @@
 ==Assignment==
-<Coming soon>
+#  Declare a student structure that contains :

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+}
-student_t get_student_info(student_t *student)
+void get_student_info(student_t *student)
+{
     /* Access the members of the structure using -> operator

@@ Line 16: / Line 16: @@
      int id;        /* Put variables separated by semicolon */
      char name[32];
-} student_t;       /* Name of the structure, _t means "type" */
+} student_t;       /* Name of the structure read as "student type" */
 void main()
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 <BR/>
 == Declare and use structure ==