{"id":12132,"date":"2022-10-29T05:07:16","date_gmt":"2022-10-29T05:07:16","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=12132"},"modified":"2023-09-20T16:46:29","modified_gmt":"2023-09-20T11:16:29","slug":"microcontroller-embedded-c-programming-lecture-124-for-loop-exercise","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/microcontroller-embedded-c-programming-lecture-124-for-loop-exercise\/","title":{"rendered":"Microcontroller Embedded C Programming lecture 124| ‘for’ loop exercise"},"content":{"rendered":"
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‘for’ loop exercise<\/span><\/strong><\/h1>\n
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In this comprehensive guide, we will delve deep into ‘for’ loops, one of the fundamental control structures in programming. We will not only explain the syntax but also provide a practical exercise to solidify your understanding. So, let’s get started!<\/span><\/p>\n

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Exercise:<\/strong><\/span><\/p>\n

           Write the program for printing even numbers using a ‘for’ loop. <\/span><\/span><\/p>\n

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\u2018for\u2019 loop syntax:<\/b><\/span><\/p>\n

The ‘for’ loop is a powerful construct used for repetitive tasks in programming. Its syntax is as follows:<\/span><\/p>\n

 for( block 1; block 2; block3)<\/span>\r\n {\r\n<\/span>          \/\/ body of for loop<\/span>\r\n }<\/span><\/pre>\n
First, you have to use a ‘for<\/span>‘ keyword, open the parenthesis, and create the body. In the parenthesis, you have to create 3 blocks by using two semicolons. <\/span><\/p>\n
Initialization (block 1):<\/strong><\/span> This block is executed only once at the beginning of the loop. It’s where you can initialize variables or perform any necessary setup. You can even include complex expressions.<\/span><\/p>\n
Evaluation (block 2):<\/strong> <\/span>This block is responsible for evaluating a condition. If the condition is true, the loop continues; otherwise, it terminates.<\/span><\/p>\n
Update (block 3):<\/strong> <\/span>The code in this block executes after each iteration of the loop body. It’s commonly used for incrementing or decrementing variables to control the loop.<\/span><\/p>\n
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Practical Exercise: Printing Even Numbers<\/span><\/strong><\/p>\n
Let’s apply our knowledge of ‘for’ loops to a practical exercise. We’ll write a program in C that prints even numbers within a given range.<\/span><\/p>\n
How to use a for loop here?<\/strong><\/span><\/p>\n
The code is shown below.<\/span><\/p>\n
You know that the first block is for some initialization or you can put any expression you want here, which will be executed only one time.  <\/span>So, you can put anything you want in block 1. <\/span><\/p>\n
For example, I can even put this printf statement in block 1. So, don’t give the semicolon, and by giving a comma, I can even give even =0 statement. <\/span>All these are legal activities. Because, this is executed only one time, that is for the very first time. <\/span><\/p>\n
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The second block is for evaluation. <\/span><\/p>\n
Here, our evaluation is, we want to check whether start_num <= end_num. That’s why I would use start_num <= end_num for evaluation( in block 2). <\/span><\/p>\n
And after that, I would just use the same logic that is if( start_num % 2). So, if it is 0, then I would print this statement, that is printf(\u201c%4d\\t\u201d, start_num). The logic is the same. And after that, I’m going to increment even++ here. This is a body of the for loop.<\/span><\/p>\n
Here you have to increment the start_num. So, that you can place it in block 3, start_num++. Because start_num++ is executed after the body is executed.<\/span><\/p>\n
You can also keep start_ num++ in after the body also, in that case, you can leave the block 3 space empty. No problem with that. <\/span><\/p>\n
#include<\/span><stdio.h>\r\n#include<\/span><stdint.h>\r\n\r\nvoid<\/span> wait_for_user_input(void<\/span>);\r\n\r\nint<\/span> main(void<\/span>)\r\n{\r\n    int32_t<\/span> start_num , end_num;\r\n    uint32_t<\/span> even;\r\n    printf<\/span>(\"Enter starting and ending numbers(give space between 2 nos):\");\r\n    scanf<\/span>(\"%d %d\",&start_num,&end_num);\r\n\r\n    if<\/span>(end_num < start_num){\r\n      \/\/error<\/span>\r\n         printf<\/span>(\"ending number should be > starting number\\n\");\r\n         wait_for_user_input();\r\n         return<\/span> 0;\r\n     }\r\n\r\n    for(printf(\"Even numbers are :\\n\"), even=0; start_num <= end_num ; start_num++ )<\/strong><\/span>\r\n      {  <\/strong><\/span>\r\n       if( ! (start_num % 2 ) ){<\/strong><\/span>\r\n              printf(\"%4d\\t\",start_num);<\/strong><\/span>\r\n              even++;<\/strong><\/span>\r\n          }<\/strong><\/span>\r\n       }\r\n       printf<\/span>(\"\\nTotal even numbers : %u\\n\",even);\r\n       wait_for_user_input();\r\n      }\r\n\r\n\r\nvoid<\/span> wait_for_user_input(void<\/span>)\r\n{\r\n      printf(\"Press enter key to exit this application\");\r\n\r\n   while<\/span>(getchar() != '\\n')\r\n   {\r\n          \/\/just read the input buffer and do nothing<\/span>\r\n   }\r\n   getchar();\r\n}<\/pre>\n
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Let me again explain this ‘for’ loop. <\/span><\/p>\n
How it executes? <\/span><\/strong><\/p>\n
To comprehend how the ‘for’ loop works in our exercise:<\/span><\/p>\n