{"id":56996,"date":"2019-01-15T21:49:20","date_gmt":"2019-01-15T13:49:20","guid":{"rendered":"http:\/\/itteacheritfreelance.hk\/test\/wordpress\/?p=56996"},"modified":"2019-01-15T21:49:41","modified_gmt":"2019-01-15T13:49:41","slug":"c-c-programming-c%e8%af%ad%e8%a8%80-%e7%bc%96%e7%a8%8b-%e8%af%ad%e8%a8%80-%e6%95%99%e5%ad%b8","status":"publish","type":"post","link":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/2019\/01\/15\/c-c-programming-c%e8%af%ad%e8%a8%80-%e7%bc%96%e7%a8%8b-%e8%af%ad%e8%a8%80-%e6%95%99%e5%ad%b8\/","title":{"rendered":"C C++ programming C\u8bed\u8a00 \u7f16\u7a0b \u8bed\u8a00 \u6559\u5b78"},"content":{"rendered":"\n

getchar()、putchar()：
<\/h2>\n\n\n\n

#include < cstdio >\n#include < cstdlib >\n\nint main() {\n    printf(\"請輸入一個字元：\");\n    char c = getchar();\n    putchar(c);\n    putchar('\\n');\n    system(\"PAUSE\");\n    return 0;\n}<\/code><\/pre>\n\n\n\ngetchar()取得使用者輸入的字元，putchar()輸出一個字元。<\/p>\n\n\n\n
gets()、puts()：
gets()會取得使用者的輸入字串，不包括按下Enter的換行字元碼，puts()用來輸出字串，並直接進行換行。<\/p>\n\n\n\n
<\/figure><\/li><\/ul>#include < cstdio >\n#include < cstdlib >\n\nint main(void) {\n    char str[20];\n    puts(\"請輸入字串：\");\n    gets(str);\n    puts(\"輸入的字串為：\");\n    puts(str);\n    system(\"PAUSE\");\n    return 0;\n}<\/code><\/pre>\n\n\n\n格式控制器、格式旗標(cout)<\/h2>\n\n\n\ncout有預設的輸出格式，也可以自行指定格式，像endl就是格式控制器的一種，它會輸出new line字元至串流中，格式控制器只會影響目前正在處理的串流，串流處理結束後即回復成預設的格式，格式控制器也可以指定參數，如果要使用具有參數的格式控制器，必須含入iomanip這個標頭檔案，下面為簡單的使用。<\/p>\n\n\n\n
#include <iostream> \n#include <iomanip>\nusing namespace std;\n\nint main() {\n    cout << oct << 30 << endl;    \/\/8進位顯示 \n    cout << hex << 30 << endl;    \/\/16進位顯示 \n    cout << setw(2) << 5 << endl; \/\/寬度為2\n    system(\"PAUSE\");\n    return 0;\n}<\/code><\/pre>\n\n\n\n
格式控制器可以改變目前的串流格式，如果想要讓所有的串流都維持特定格式，可以使用格式化旗標，使用setf()與unsetf()來設定與取消格式化旗標，下面為簡單的示範。<\/p>\n\n\n\n
#include <iostream> \nusing namespace std;\n\nint main() {\n    cout.unsetf(ios::dec);              \n    cout.setf(ios::hex); \n    cout << 120 << endl;\n    cout << 50 << endl;\n\n    cout.setf(ios::dec);\n    cout.setf(ios::scientific);\n    cout << 50.25 << endl;\n\n    system(\"PAUSE\");\n    return 0;\n}<\/code><\/pre>\n\n\n\nBasic types of Variables<\/h2>\n\n\n\nEach variable while declaration must be given a datatype, on which the memory assigned to the variable depends. Following are the basic types of variables,<\/p>\n\n\n\nbool<\/code><\/td> For variable to store boolean<\/a> values( True or False )<\/td><\/tr>
char<\/code><\/td> For variables to store character types.<\/td><\/tr>
int<\/code><\/td> for variable with integral values<\/td><\/tr>
float<\/code> and double<\/code> are also types for variables with large and floating point values<\/td><\/tr><\/tbody><\/table>Declaration and Initialization<\/h2>\n\n\n\nVariable must be declared before they are used. Usually it is preferred to declare them at the starting of the program, but in C++ they can be declared in the middle of program too, but must be done before using them.<\/p>\n\n\n\n
For example:<\/p>\n\n\n\n
int i;      \/\/ declared but not initialised\nchar c; \nint i, j, k;  \/\/ Multiple declaration\n<\/code><\/pre>\n\n\n\nInitialization means assigning value to an already declared variable,<\/p>\n\n\n\n
int i;   \/\/ declaration\ni = 10;  \/\/ initialization\n<\/code><\/pre>\n\n\n\nInitialization and declaration can be done in one single step also,<\/p>\n\n\n\n
int i=10;         \/\/initialization and declaration in same step\nint i=10, j=11;\n<\/code><\/pre>\n\n\n\nIf a variable is declared and not initialized by default it will hold a garbage value. Also, if a variable is once declared and if try to declare it again, we will get a compile time error.<\/p>\n\n\n\n
int i,j;\ni=10;\nj=20;\nint j=i+j;   \/\/compile time error, cannot redeclare a variable in same scope\n<\/code><\/pre>\n\n\n\nC\/C++<\/figcaption><\/figure>IT Freelance<\/figcaption><\/figure><\/body><\/html>\n","protected":false},"excerpt":{"rendered":"Introduction to C++
\nC++, as we all know is an extension to C language and was developed by Bjarne stroustrup at bell labs. C++ is an intermediate level language, as it comprises a confirmation of both high level and low level language features. C++ is a statically typed, free form, multiparadigm, compiled general-purpose language.<\/p>\n
C++ is an Object Oriented Programming language but is not purely Object Oriented. Its features like Friend and Virtual, violate some of the very important OOPS features, rendering this language unworthy of being called completely Object Oriented. Its a middle level language \u95b1\u8b80\u5168\u6587 →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":175,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"slim_seo":[],"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[56,2],"tags":[1536,376,1542,1541,1544,1540,1537,1535,1538,1543,1550,378,377,318,1539,1373,367,334,335,95,995,509,363,384,321,369,353,368,96,348,350,316,317,98,87,88,93,92,86,90,89],"jetpack_publicize_connections":[],"aioseo_notices":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/itteacheritfreelance.hk\/test\/wordpress\/wp-content\/uploads\/2016\/04\/c-c-programming-for-hackers-part-1-introduction.1280x600.jpg?fit=1280%2C600&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p7prtj-ePi","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/comments?post=56996"}],"version-history":[{"count":2,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996\/revisions"}],"predecessor-version":[{"id":57009,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996\/revisions\/57009"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/media\/175"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/media?parent=56996"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/categories?post=56996"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/tags?post=56996"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

`bool<\/code><\/td>`	For variable to store boolean<\/a> values( True or False )<\/td><\/tr>
`char<\/code><\/td>`	For variables to store character types.<\/td><\/tr>
`int<\/code><\/td>`	for variable with integral values<\/td><\/tr>
float<\/code> and double<\/code> are also types for variables with large and floating point values<\/td><\/tr><\/tbody><\/table>Declaration and Initialization<\/h2>\n\n\n\nVariable must be declared before they are used. Usually it is preferred to declare them at the starting of the program, but in C++ they can be declared in the middle of program too, but must be done before using them.<\/p>\n\n\n\n For example:<\/p>\n\n\n\n int i; \/\/ declared but not initialised\nchar c; \nint i, j, k; \/\/ Multiple declaration\n<\/code><\/pre>\n\n\n\nInitialization means assigning value to an already declared variable,<\/p>\n\n\n\n int i; \/\/ declaration\ni = 10; \/\/ initialization\n<\/code><\/pre>\n\n\n\nInitialization and declaration can be done in one single step also,<\/p>\n\n\n\n int i=10; \/\/initialization and declaration in same step\nint i=10, j=11;\n<\/code><\/pre>\n\n\n\nIf a variable is declared and not initialized by default it will hold a garbage value. Also, if a variable is once declared and if try to declare it again, we will get a compile time error.<\/p>\n\n\n\n int i,j;\ni=10;\nj=20;\nint j=i+j; \/\/compile time error, cannot redeclare a variable in same scope\n<\/code><\/pre>\n\n\n\nC\/C++<\/figcaption><\/figure>IT Freelance<\/figcaption><\/figure><\/body><\/html>\n","protected":false},"excerpt":{"rendered":"Introduction to C++ \nC++, as we all know is an extension to C language and was developed by Bjarne stroustrup at bell labs. C++ is an intermediate level language, as it comprises a confirmation of both high level and low level language features. C++ is a statically typed, free form, multiparadigm, compiled general-purpose language.<\/p>\n C++ is an Object Oriented Programming language but is not purely Object Oriented. Its features like Friend and Virtual, violate some of the very important OOPS features, rendering this language unworthy of being called completely Object Oriented. Its a middle level language \u95b1\u8b80\u5168\u6587 →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":175,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"slim_seo":[],"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[56,2],"tags":[1536,376,1542,1541,1544,1540,1537,1535,1538,1543,1550,378,377,318,1539,1373,367,334,335,95,995,509,363,384,321,369,353,368,96,348,350,316,317,98,87,88,93,92,86,90,89],"jetpack_publicize_connections":[],"aioseo_notices":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/itteacheritfreelance.hk\/test\/wordpress\/wp-content\/uploads\/2016\/04\/c-c-programming-for-hackers-part-1-introduction.1280x600.jpg?fit=1280%2C600&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p7prtj-ePi","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/comments?post=56996"}],"version-history":[{"count":2,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996\/revisions"}],"predecessor-version":[{"id":57009,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/posts\/56996\/revisions\/57009"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/media\/175"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/media?parent=56996"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/categories?post=56996"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/test\/wordpress\/wp-json\/wp\/v2\/tags?post=56996"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}