CString of MFC skills
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This document discusses methods for finding and extracting substrings from a CString object in C++. It covers the Find() function, which searches for a substring within the CString and returns its index or -1 if not found. Using Find(), it demonstrates how to retrieve the substring to the left, right, or between two search terms. It also notes some considerations for Find(), such as it returning 0 when searching for an empty string.
CString of MFC skills
- 2. Outline • Find()函數 • 找fg左全部 • 找fg左3位 • 取出特定字之間的字 • 找fg右全部 • 找fg右3位 • Find()注意事項
- 3. Find()函數找fg CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString goal(“fg”); int goalIndex = sample.Find(goal); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789…
- 4. 找fg左全部 CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString goal(“fg”); int goalIndex = sample.Find(goal); CString result = sample.Left(goalIndex); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789…
- 5. 找fg左3位 CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString goal(“fg”); int goalIndex = sample.Find(goal); const int charAmount = 3; CString result = sample.Mid(goalIndex-charAmount, charAmount); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789… charAmount
- 6. 取出特定字之間的字 CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString begin(“bc”), end(“fg”); int beginIndex = sample.Find(begin); int endIndex = sample.Find(end); CString result = sample.Mid(beginIndex+begin.GetLength(), endIndex-beginIndex+begin.GetLength()); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789… +begin.GetLength()
- 7. 找fg右全部 CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString goal(“fg”); int goalIndex = sample.Find(goal); CString result = sample.Right(sample.GetLength()- goalIndex+goalIndex.GetLength()); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789… +goalIndex.GetLength()
- 8. 找fg右3位 CString sample = “abcdefghijklmnopqrstuvwxyz”; const CString goal(“fg”); int goalIndex = sample.Find(goal); const int charAmount = 3; CString result = sample.Mid(abcIndex+goalIndex.GetLength(), charAmount); CString::Find()的return 找到: 0~n 找不到: -1 abcdefghijk… 0123456789… charAmount +goalIndex.GetLength()
- 9. Find()注意事項 CString sample = “abcdefghijklmnopqrstuvwxyz”; int errorIndex = sample.Find(“llllll”); int emptyIndex = sample.Find(“”); errorIndex: -1 emptyIndex: 0