{"id":15967,"date":"2022-10-13T18:05:26","date_gmt":"2022-10-13T12:35:26","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-pointer-c-language-closed\/"},"modified":"2022-10-13T18:05:26","modified_gmt":"2022-10-13T12:35:26","slug":"solved-pointer-c-language-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-pointer-c-language-closed\/","title":{"rendered":"[Solved] Pointer C Language [closed]"},"content":{"rendered":"

[ad_1]
\n<\/p>\n

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What does this function do?<\/p>\n<\/blockquote>\n

It concatenates two strings, i.e. it’s doing the same as the standard strcat<\/code> function. See https:\/\/man7.org\/linux\/man-pages\/man3\/strcat.3.html<\/a><\/p>\n

Assume the input is “Hello World”.<\/p>\n

Just when the function is called, some where in memory it looks like:<\/p>\n

String1: Hello\\0\n         ^\n         |\n         s1\n\nString2: World\\0\n         ^\n         |\n         s2\n<\/code><\/pre>\n
Now this part<\/p>\n
while (*s1 != '\\0') {\n  ++s1;\n} \n<\/code><\/pre>\n
Moves the pointer s1<\/code> to the end of String1<\/code>. So you have<\/p>\n
String1: Hello\\0\n               ^\n               |\n               s1\n\nString2: World\\0\n         ^\n         |\n         s2\n<\/code><\/pre>\n
Then this part<\/p>\n
for (; *s1 = *s2; ++s1, ++s2) {\n  ; \/\/ empty statement\n} \n<\/code><\/pre>\n
copies characters from String2<\/code> (using s2<\/code>) to the end of String1<\/code> (using s1<\/code>).<\/p>\n
After one loop, you’ll have:<\/p>\n
String1: HelloWorldW\n                    ^\n                    |\n                    s1\n\nString2: World\\0\n          ^\n          |\n          s2\n<\/code><\/pre>\n
After one more loop, you’ll have:<\/p>\n
String1: HelloWorldWo\n                     ^\n                     |\n                     s1\n\nString2: World\\0\n           ^\n           |\n           s2\n<\/code><\/pre>\n
and so on.<\/p>\n
In the end you’ll have<\/p>\n
String1: HelloWorld\\0\n                     ^\n                     |\n                     s1\n\nString2: World\\0\n                ^\n                |\n                s2\n<\/code><\/pre>\n
Net result: String2<\/code> was concatenated to String1<\/code><\/p>\n
A few more words about for (; *s1 = *s2; ++s1, ++s2) {<\/code><\/p>\n
The ; says: no initialization needed\n\nThe *s1 = *s2; says: Copy the char that s2 points to to the memory that s1 points to. \nFurther, it serves as \"end-of-loop\" condition, i.e. the loop will end when a \\0 has \nbeen copied\n\nThe ++s1, ++s2 says: Increment both pointers\n<\/code><\/pre>\n
In this way characters from String2<\/code> are one-by-one copied to the end of String1<\/code><\/p>\n
BTW: Notice that the main<\/code> function is unsafe as too little memory is reserved for String1<\/code><\/p>\n<\/p><\/div>\n
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            0<\/span> <\/p><\/div>\n<\/div>\n
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solved Pointer C Language [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] What does this function do? It concatenates two strings, i.e. it’s doing the same as the standard strcat function. See https:\/\/man7.org\/linux\/man-pages\/man3\/strcat.3.html Assume the input is “Hello World”. Just when the function is called, some where in memory it looks like: String1: Hello\\0 ^ | s1 String2: World\\0 ^ | s2 Now this part while … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324,712],"class_list":["post-15967","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c","tag-pointers"],"yoast_head":"\n[Solved] Pointer C Language [closed] - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-pointer-c-language-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Pointer C Language [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] What does this function do? 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