实现两个超大无符号整数的加法

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实现两个超大无符号整数的加法（现有基本数据类型无法存储）

#include <stdio.h>#include <string.h>#include <stdlib.h>int AddBigNum ( const char *pA, const char *pB, char *pSum, int nSumMaxLen);int main ( int argc, char **argv ){int len;char str[1000];char str1[1000];char str2[1000];scanf("%s",str);scanf("%s",str1);len = AddBigNum ( str, str1, str2, 0);if( str2[ 0 ] == '0'){for ( int i = 1; i < len ; i++){printf("%c", str2[ i ]);}}else {for ( int i = 0; i < len; i++){printf("%c", str2[i]);}}putchar ( 10 );}int AddBigNum ( const char *pA, const char *pB, char *pSum, int nSumMaxLen){int len_a = strlen ( pA );//计算字符串A长度int len_b = strlen ( pB );//计算字符串B长度const char *max;const char *min;int len_max = (len_a -len_b >= 0) ? len_a : len_b;//把字符串长的给len_maxint len_min = (len_a - len_b < 0) ? len_a : len_b;//把字符串短的给len_minmax = (len_a - len_b >= 0) ? pA : pB;//把字符串长的给maxmin = (len_a - len_b < 0) ? pA : pB;//把字符串短的给minnSumMaxLen = len_max + 1;//和的长度加1 进位pSum[ 0 ] = '0';//和的最高位给0for( int i = 0; i < len_max - len_min; ++i){pSum[ i + 1 ] = max[ i ];//字符串长的前len_max-len_min 字符给到pSum}for( int i = len_max - len_min; i < len_max; ++i){if( pA[ i ] + pB[ i - len_max + len_min ] - '0' > '9' )//判断有无进位{pSum[ i + 1 ] = max[ i ] + min[ i - len_a + len_b] - '0' - 10;//本位减10int j = i ;while ( (pSum[ j ] = pSum[ j ] + 1) > '9' )//进位加1 判断是否还需要进位{pSum[ j ] = pSum[ j ] - 10;j-- ;}}else{pSum[ i + 1 ] = max[ i ] + min[ i - len_a + len_b ] - '0';//不需要进位}}return nSumMaxLen;}

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