CC++常用函數(shù).doc

C/C+常用函數(shù) 分類： C/C+基礎(chǔ) 2010-03-14 00:22 465人閱讀 評論(0) 收藏 舉報(bào) Strstrstrncpy strcpy_s /VC6.0沒有此函數(shù)strcpyCString 轉(zhuǎn)換 stringCString 轉(zhuǎn)換 char數(shù)組String 轉(zhuǎn)換 doubleChar * 轉(zhuǎn)換 stringInt 轉(zhuǎn)換stringString 轉(zhuǎn)換charatolConvert string to long integer (function)strtoulConvert string to unsigned long integer (function)strtodConvert string to double (function)atoiConvert string to integer (function)atofConvert string to double (function)strtolConvert string to long integer (function)/* strstr example */#include using namespace std;int main ()char str =This is a imple string;char * pch;pch = strstr (str,s); /pch沒有開辟新的地址，還是指向str的地址空間，次例輸出可以說明問題strncpy (pch,sample,6);puts (str);strcpy(st,pch);cout*pchendl;/此輸出只有一個(gè)字符，若想要全部還需要一個(gè)緩沖區(qū)char a2;char* b;a0=;/不能為a0=w; 此為兩個(gè)字符，還有一個(gè)/0a1=50;b=strstr(!#$,a);return 0;/*strncpy example */#include #include int main () char str1= To be or not to be; char str26; strncpy (str2,str1,5);/將str1前五個(gè)字符復(fù)值給str2 str25=/0; puts (str2); return 0;/*strcpy_s(VC6.0沒有此函數(shù))和strcpy()*/strcpy_s和strcpy()函數(shù)的功能應(yīng)該一樣的。strcpy函數(shù)，就象gets函數(shù)一樣，它沒有方法來保證有效的緩沖區(qū)尺寸，所以它只能假定緩沖足夠大來容納要拷貝的字符串。在程序運(yùn)行時(shí)，這將導(dǎo)致不可預(yù)料的行為。用strcpy_s就可以避免這些不可預(yù)料的行為。這個(gè)函數(shù)用兩個(gè)參數(shù)、三個(gè)參數(shù)都可以，只要可以保證緩沖區(qū)大小。三個(gè)參數(shù)時(shí)：errno_t strcpy_s( char *strDestination, size_t numberOfElements, const char *strSource );兩個(gè)參數(shù)時(shí)：errno_t strcpy_s( char (&strDestination)size, const char *strSource ); / C+ only #include#includeusing namespace std;void main( ) char *str1=NULL;str1=new char20;char str7;strcpy_s(str1,20,hello world);/三個(gè)參數(shù)strcpy_s(str,hello);/兩個(gè)參數(shù)但如果：char *str=new char7;會出錯(cuò)：提示不支持兩個(gè)參數(shù)coutstrlen(str1)strlen(str1)strlen(str)strlen(str)endl;printf(str1);printf(/n);coutstrGetWindowText(str);info.account = str.GetBuffer(0);str.ReleaseBuffer();2.CString 轉(zhuǎn)換 char數(shù)組char *p;char c10;p=str.GetBuffer(str.GetLength();str.ReleaseBuffer(); strcpy(c,p);3.string to double 10#include 11#include 12#include 1314usingnamespace std;1516int main() 17 string s =123;18 double n = atof(s.c_str();19 /int n = atoi(s.c_str();20 21 cout n endl;224.Char * 轉(zhuǎn)換 stringchar* cExpressionstring str(cExpression);5.int轉(zhuǎn)stringstring轉(zhuǎn)char#include #include #include using namespace std; int main() stringstream sstr; /-int轉(zhuǎn)string- int a=100; string str; sstrstr; coutstrendl; /-string轉(zhuǎn)char- sstr.clear();/如果你想通過使用同一stringstream對象