DSP

atoi() & itoa()&atol()<oa()函数的实现

2019-07-13 13:02发布

站内文章 / DSP
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#include "stdio.h" #include "conio.h" #include #include typedef long long __int64; //64位 需要设备支持64 否则结果是不对的 /**************************************/ long 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(const char *nptr) { return (int)atol(nptr); } #ifndef _NO_INT64 __int64 _atoi64(const char *nptr) { int c; /* current char */ __int64 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 */ } #endif /* _NO_INT64 */ char* _itoa(int value, char* string, int radix) { char tmp[33]; char* tp = tmp; int i; unsigned v; int sign; char* sp; if (radix > 36 || radix <= 1) { return 0; } sign = (radix == 10 && value < 0); if (sign) v = -value; else v = (unsigned)value; while (v || tp == tmp) { i = v % radix; v = v / radix; if (i < 10) *tp++ = i+'0'; else *tp++ = i + 'a' - 10; } if (string == 0) string = (char*)malloc((tp-tmp)+sign+1); sp = string; if (sign) *sp++ = '-'; while (tp > tmp) *sp++ = *--tp; *sp = 0; return string; } char* _ltoa(long value, char* string, int radix) { char tmp[33]; char* tp = tmp; long i; long v; int sign; char* sp; if (radix > 36 || radix <= 1) { return 0; } sign = (radix == 10 && value < 0); if (sign) v = -value; else v = (unsigned long)value; while (v || tp == tmp) { i = v % radix; v = v / radix; if (i < 10) *tp++ = i+'0'; else *tp++ = i + 'a' - 10; } if (string == 0) string = (char*)malloc((tp-tmp)+sign+1); sp = string; if (sign) *sp++ = '-'; while (tp > tmp) *sp++ = *--tp; *sp = 0; return string; }    

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