90分求：itoa, atoi，trim 三个函数最完美的实现代码rt[解决办法]ITOAC/C++ codestatic void __cdecl xtoa (
90分求：itoa, atoi，trim 三个函数最完美的实现代码
rt
[解决办法]
ITOA
- C/C++ code
static void __cdecl xtoa ( unsigned long val, char *buf, unsigned radix, int is_neg ){ char *p; /* pointer to traverse string */ char *firstdig; /* pointer to first digit */ char temp; /* temp char */ unsigned digval; /* value of digit */ p = buf; if (is_neg) { /* negative, so output '-' and negate */ *p++ = '-'; val = (unsigned long)(-(long)val); } firstdig = p; /* save pointer to first digit */ do { digval = (unsigned) (val % radix); val /= radix; /* get next digit */ /* convert to ascii and store */ if (digval > 9) *p++ = (char) (digval - 10 + 'a'); /* a letter */ else *p++ = (char) (digval + '0'); /* a digit */ } while (val > 0); /* We now have the digit of the number in the buffer, but in reverse order. Thus we reverse them now. */ *p-- = '\0'; /* terminate string; p points to last digit */ do { temp = *p; *p = *firstdig; *firstdig = temp; /* swap *p and *firstdig */ --p; ++firstdig; /* advance to next two digits */ } while (firstdig < p); /* repeat until halfway */}/* Actual functions just call conversion helper with neg flag set correctly, and return pointer to buffer. */char * __cdecl _itoa ( int val, char *buf, int radix ){ if (radix == 10 && val < 0) xtoa((unsigned long)val, buf, radix, 1); else xtoa((unsigned long)(unsigned int)val, buf, radix, 0); return buf;}
[解决办法]
ATOI
- C/C++ code
#include <CTYPE.H>long __cdecl atol( const char *nptr ){ int c; /* current char */ long total; /* current total */ int sign; /* if '-', then negative, otherwise positive */ /* skip whitespace */ while ( isspace((int)(unsigned char)*nptr) ) ++nptr; c = (int)(unsigned char)*nptr++; sign = c; /* save sign indication */ if (c == '-' || c == '+') c = (int)(unsigned char)*nptr++; /* skip sign */ total = 0; while (isdigit(c)) { total = 10 * total + (c - '0'); /* accumulate digit */ c = (int)(unsigned char)*nptr++; /* get next char */ } if (sign == '-') return -total; else return total; /* return result, negated if necessary */}/****int atoi(char *nptr) - Convert string to long**Purpose:* Converts ASCII string pointed to by nptr to binary.* Overflow is not detected. Because of this, we can just use* atol().**Entry:* nptr = ptr to string to convert**Exit:* return int value of the string**Exceptions:* None - overflow is not detected.********************************************************************************/int __cdecl atoi( const char *nptr ){ return (int)atol(nptr);}
[解决办法]
TRIM
- C/C++ code
#include <windows.h>#include <tchar.h>#define LINE_LEN 256 static void TrimLeft( const TCHAR* pszParam, TCHAR* pszResult ) { TCHAR szBuffer[LINE_LEN]; _tcscpy(szBuffer, "\0"); if ( (TRUE != ::IsBadStringPtr(pszParam, LINE_LEN)) && (_tcslen(pszParam) > 0) ) { DWORD dwIndex = 0; while ( (dwIndex < _tcslen(pszParam)) && (pszParam[dwIndex] == ' ') ) dwIndex++; if (dwIndex < _tcslen(pszParam)) _tcscpy(szBuffer, &pszParam[dwIndex]); } // if _tcscpy(pszResult, szBuffer); } // // Trims trailing spaces and control characters from a string // static void TrimRight( const TCHAR* pszParam, TCHAR* pszResult ) { TCHAR szBuffer[LINE_LEN]; _tcscpy(szBuffer, "\0"); if ( (TRUE != ::IsBadStringPtr(pszParam, LINE_LEN)) && (_tcslen(pszParam) > 0) ) { size_t nIndex = _tcslen(pszParam) - 1; while ( (nIndex >= 0) && (pszParam[nIndex] == ' ') ) nIndex--; if (nIndex >= 0) { memcpy( (PBYTE)szBuffer, (PBYTE)pszParam, (nIndex + 1)*sizeof(TCHAR) ); szBuffer[nIndex+1] = 0; } // if } // if _tcscpy(pszResult, szBuffer); } // // Trims leading and trailing spaces and control characters from a string // static void Trim( const TCHAR* pszParam, TCHAR* pszResult ) { TrimLeft(pszParam, pszResult); TrimRight(pszParam, pszResult); }