PHP 溢出 加减运算 超大整数
分享一个溢出整数加减的运算函数，刚刚写的，对于溢出的整数可以用这个来进行加减运算。遗憾的几点是：
一代码太多；二只有加减运算，乘除取余都没有；
其实还有一个更简便的方式就是用SQL数据库的：SELECT n1+n2;
mysql> SELECT 11234123413241341234123412341234+1;+------------------------------------+| 11234123413241341234123412341234+1 |+------------------------------------+| 11234123413241341234123412341235 |+------------------------------------+1 row in set (0.00 sec)mysql> SELECT 11234123413241341234123412341234*12341234123;+----------------------------------------------+| 11234123413241341234123412341234*12341234123 |+----------------------------------------------+| 138642947209487270472850788378836360727782 |+----------------------------------------------+1 row in set (0.00 sec)
如果有更好的方法，请随时回帖或者发个信息给我。欢迎探讨。
/* big int operate [by fuzb 20130826] */function bigintO($num1,$op,$num2){ $arr = array(); $endop = ''; $num1o = $num1; $num2o = $num2; if($num1 < 0) { $c1 = -1; $num1 = preg_replace('/^(-)/','',$num1); } else { $c1 = 1; } if($num2 < 0) { $c2 = -1; $num2 = preg_replace('/^(-)/','',$num2); } else { $c2 = 1; } $len1 = strlen($num1); $len2 = strlen($num2); $len = max(strlen($num1),strlen($num2)); if($len1 < $len) $num1 = str_pad('0',$len - $len1).$num1; if($len2 < $len) $num2 = str_pad('0',$len - $len2).$num2; if($op == '+') { if($c1 == $c2) { $endop = $c1 > 0 ? '':'-'; } else { $endop = abs($num1o) > abs($num2o) ? $c1:$c2; $endop = $endop > 0 ? '':'-'; } $cc = $endop == '-' ? -1:1; for($i=0; $i< $len; $i++) { $n1 = intval($num1{$i}); $n2 = intval($num2{$i}); $n = $n1*$c1+$n2*$c2; $arr[$i] = $n*$cc; } } else if($op == '-') { if($c1 < 0) { $endop = $c2 > 0 ? '-':(abs($num1o) > abs($num2o) ? '-':''); } else { $endop = $c2 > 0 ? (abs($num1o) > abs($num2o) ? '':'-'):''; } $cc = $endop == '-' ? -1:1; for($i=0;$i < $len;$i++) { $n1 = intval($num1{$i}); $n2 = intval($num2{$i}); $n = $n1*$c1-$n2*$c2; $arr[$i] = $n*$cc; } } $len = count($arr); $arr2 = array(); for($i=0;$i< $len;$i++) { if($arr[$i] < 0) { $n = $arr[$i] + 10; $arr2[$i] = $n; $j = $i-1; while(true) { if($arr2[$j] == 0) { $arr2[$j] = 9; $j--; } else { $arr2[$j]--; break; } } } else if($arr[$i] > 9) { $n = $arr[$i] - 10; $arr2[$i] = $n; $j = $i-1; while(true) { if($arr2[$j] == 9) { $arr2[$j] = 0; $j--; } else { $arr2[$j]++; break; } } } else { $arr2[$i] = $arr[$i]; } } $value = $endop.preg_replace('/^(0{1,})/','',implode($arr2)); return strlen($value) > 0 ? $value : '0';} 测试：
$a = '-12345678901234567890123456789';$b = '1';$c = bigintO($a,'+',$b);var_dump($a); var_dump($b); var_dump($c);exit();/*输出：string '-12345678901234567890123456789' (length=30)string '1' (length=1)string '-12345678901234567890123456788' (length=30)*/
回复讨论(解决方案)
php 已经提供了 BC 和 GMP 两个高精度数学运算函数库
bcadd ? Add two arbitrary precision numbersbccomp ? Compare two arbitrary precision numbersbcdiv ? Divide two arbitrary precision numbersbcmod ? Get modulus of an arbitrary precision numberbcmul ? Multiply two arbitrary precision numberbcpow ? Raise an arbitrary precision number to anotherbcpowmod ? Raise an arbitrary precision number to another, reduced by a specified modulusbcscale ? Set default scale parameter for all bc math functionsbcsqrt ? Get the square root of an arbitrary precision numberbcsub ? Subtract one arbitrary precision number from another
gmp_abs ? Absolute valuegmp_add ? Add numbersgmp_and ? Bitwise ANDgmp_clrbit ? Clear bitgmp_cmp ? Compare numbersgmp_com ? Calculates one's complementgmp_div_q ? Divide numbersgmp_div_qr ? Divide numbers and get quotient and remaindergmp_div_r ? Remainder of the division of numbersgmp_div ? 别名 gmp_div_qgmp_divexact ? Exact division of numbersgmp_fact ? Factorialgmp_gcd ? Calculate GCDgmp_gcdext ? Calculate GCD and multipliersgmp_hamdist ? Hamming distancegmp_init ? Create GMP numbergmp_intval ? Convert GMP number to integergmp_invert ? Inverse by modulogmp_jacobi ? Jacobi symbolgmp_legendre ? Legendre symbolgmp_mod ? Modulo operationgmp_mul ? Multiply numbersgmp_neg ? Negate numbergmp_nextprime ? Find next prime numbergmp_or ? Bitwise ORgmp_perfect_square ? Perfect square checkgmp_popcount ? Population countgmp_pow ? Raise number into powergmp_powm ? Raise number into power with modulogmp_prob_prime ? Check if number is "probably prime"gmp_random ? Random numbergmp_scan0 ? Scan for 0gmp_scan1 ? Scan for 1gmp_setbit ? Set bitgmp_sign ? Sign of numbergmp_sqrt ? Calculate square rootgmp_sqrtrem ? Square root with remaindergmp_strval ? Convert GMP number to stringgmp_sub ? Subtract numbersgmp_testbit ? Tests if a bit is setgmp_xor ? Bitwise XOR