I’m always mindful of the beginner when I write code for this blog. Even with my own code, I often go to pains to write things “the long way” just because I’m in the habit. Not every coder is so thoughtful. The reason is that C tends toward obfuscation. We must revel in this capability.
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\nOf course, I can write delightfully cryptic code. It’s compact. But many programmers know that it’s a tough knot to unwind in the future when you may need to revisit your obfuscated code. It’s the “what the heck was I thinking?” phenomenon. But for me, what happens is often the opposite as I initially write code unwound.<\/p>\n
Consider this code from an earlier post<\/a> on a filter I wrote to convert spaces to the non-breakable space HTML code, :<\/p>\n This code works and is understandable by most beginning C programmers, but it can be shortened. The key for me is that the while<\/em> loop terminates upon the EOF character being encountered. Therefore, the loop can be re-written with the EOF as its terminating condition, saving several lines of code.<\/p>\n You can write In this update, variable The getchar()<\/em> function returns a single character from standard input. The value is an integer, allowing the EOF constant to be read. But the expression The while<\/em> loop’s condition now both reads a character from standard input and compares the character with the EOF. If true, the loop stops.<\/p>\n Reading the expression from the inside out: This approach is how I believe most experienced C programmers would write the loop. First, it takes fewer statements. Second, it’s cryptic. When teaching, I would need to explain all the mechanics, which is what I did above. It’s easier for me, and better for the beginner, to see things done the long way and then worry about tightening the code later.<\/p>\n","protected":false},"excerpt":{"rendered":" C has the delightful tendency to be remarkably cryptic. Continue reading 2023_04_01-Lesson.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n int ch;\r\n\r\n while(1)\r\n {\r\n ch = getchar();\r\n if( ch==EOF )\r\n break;\r\n if( ch==' ' )\r\n printf(\" \");\r\n else\r\n putchar(ch);\r\n }\r\n\r\n return(0);\r\n}<\/pre>\nwhile(ch!=EOF)<\/code> to start the loop, providing that you first initialize variable ch<\/code>:<\/p>\n2024_05_04-Lesson-a.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n int ch = '\\0';\r\n\r\n while(ch!=EOF)\r\n {\r\n ch = getchar();\r\n if( ch==' ' )\r\n printf(\" \");\r\n else\r\n putchar(ch);\r\n }\r\n\r\n return(0);\r\n}<\/pre>\nch<\/code> is initialized to the null character. The while<\/em> condition works because ch<\/code> already holds a value, which isn’t the EOF. Then the rest of the loop continues, converting space characters from standard input into the HTML unbreakable space code. Yet more compacting is possible.<\/p>\nch = getchar()<\/code> also generates a value, the character returned. Therefore, this statement can be used as the while<\/em> loop’s condition:<\/p>\n2024_05_04-Lesson-b.c<\/a><\/h3>\n
\r\n#include <stdio.h>\r\n\r\nint main()\r\n{\r\n int ch;\r\n\r\n while( (ch=getchar()) != EOF )\r\n {\r\n if( ch==' ' )\r\n printf(\" \");\r\n else\r\n putchar(ch);\r\n }\r\n\r\n return(0);\r\n}<\/pre>\nch=getchar()<\/code> reads a character from standard input and stores it in variable ch<\/code>. This expression is enclosed in parentheses, where it evaluates as the character returned, the value in variable ch<\/code>. This value is then compared with the EOF. If it’s not equal, the loop repeats: The character read is compared with a space, replaced if true, output otherwise. When the character is the EOF, the loop stops.<\/p>\n