在C或C++中有没有对字符串截取前某几位的函数 c++ 如何截取字符串的后几位
\u5728C\u6216C++\u4e2d\u6709\u6ca1\u6709\u5bf9\u5b57\u7b26\u4e32\u622a\u53d6\u524d\u67d0\u51e0\u4f4d\u7684\u51fd\u6570\u622a\u53d6\u524d\u51e0\u4f4d\u7684\u610f\u601d\u662f\u622a\u53d6\u5b57\u7b26\u4e32\u524d\u67d0\u51e0\u4e2a\u5b57\u7b26\u5417\uff1f\u5982\u679c\u662f\u7684\u8bdd\uff0cC\u8bed\u8a00\u4e2d\u6709:
char * strncpy ( char * destination, const char * source, size_t num );
\u53ef\u4ee5\u5c06\u524d\u51e0\u4f4d\u590d\u5236\u5230\u65b0\u7684\u5b57\u7b26\u4e32\u4e2d\u4f7f\u7528\u3002
C++\u4e2d\u6709:
string substr (size_t pos = 0, size_t len = npos) const;
\u6d4b\u8bd5\u6e90\u7801\u89c1\u4ee5\u4e0b\u94fe\u63a5\uff1a
strncpy: http://www.cplusplus.com/reference/cstring/strncpy/
string::substr: http://www.cplusplus.com/reference/string/string/substr/
\u5e0c\u671b\u80fd\u591f\u5e2e\u5230\u4f60\u3002
char *substrend(char * str, int n);
char substrend(char *str, int n)
{
char * substr = (char*) malloc (n+1);
int length = strlen(str);
if(n >= length)//\u82e5\u622a\u53d6\u957f\u5ea6\u5927\u4e8e\u5b57\u7b26\u4e32\u957f\u5ea6\uff0c\u5219\u76f4\u63a5\u622a\u53d6\u5168\u90e8\u5b57\u7b26\u4e32
{
strcpy(substr, str);
return substr;
}
int k = 0;
for(int i = strlen(str) - n - 1; i < strlen(str); i++)
{
substr[k++] = str[i];
}
substr[k] = '\0';
return substr;
}
str.substr(0, 3); //0表示str的起始位置，就是第一个字符的位置；3表示截取几个字符
并返回截取后的新的字符串
可以用substr函数
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