普通大数运算模板
const int MAXSIZE = 200;
void Add(char *str1, char *str2, char *str3);
void Minus(char *str1, char *str2, char *str3);
void Mul(char *str1, char *str2, char *str3);
void Div(char *str1, char *str2, char *str3);
int main(void)
{
{
char str1[MAXSIZE], str2[MAXSIZE], str3[MAXSIZE];
while( scanf("%s %s", str1, str2) == 2 )
{
if( strcmp(str1, "0") )
{
memset(str3, '0', sizeof(str3)); // !!!!!
Add(str1, str2, str3);
printf("%s\n", str3);
memset(str3, '0', sizeof(str3));
Minus(str1, str2, str3);
printf("%s\n", str3);
memset(str3, '0', sizeof(str3));
Mul(str1, str2, str3);
printf("%s\n", str3);
memset(str3, '0', sizeof(str3));
Div(str1, str2, str3);
printf("%s\n", str3);
}
else
{
if( strcmp(str2, "0") )
printf("%s\n-%s\n0\n0\n", str2, str2);
else printf("0\n0\n0\n0\n");
}
}
return 0;
}
加法 ：
void Add(char *str1, char *str2, char *str3)
{// str3 = str1 + str2;
int i, j, i1, i2, tmp, carry;
int len1 = strlen(str1), len2 = strlen(str2);
char ch;
i1 = len1-1; i2 = len2-1;
j = carry = 0;
for( ; i1 >= 0 && i2 >= 0; ++j, --i1, --i2 )
{
tmp = str1[i1]-'0'+str2[i2]-'0'+carry;
carry = tmp/10;
str3[j] = tmp%10+'0';
}
while( i1 >= 0 )
{
tmp = str1[i1--]-'0'+carry;
carry = tmp/10;
str3[j++] = tmp%10+'0';
}
while( i2 >= 0 )
{
tmp = str2[i2--]-'0'+carry;
carry = tmp/10;
str3[j++] = tmp%10+'0';
}
if( carry ) str3[j++] = carry+'0';
str3[j] = '\0';
for( i=0, --j; i < j; ++i, --j )
{
ch = str3; str3 = str3[j]; str3[j] = ch;
}
}
减法：
void Minus(char *str1, char *str2, char *str3)
{// str3 = str1-str2 (str1 > str2)
int i, j, i1, i2, tmp, carry;
int len1 = strlen(str1), len2 = strlen(str2);
char ch;
i1 = len1-1; i2 = len2-1;
j = carry = 0;
while( i2 >= 0 )
{
tmp = str1[i1]-str2[i2]-carry;
if( tmp < 0 )
{
str3[j] = tmp+10+'0'; carry = 1;
}
else
{
str3[j] = tmp+'0'; carry = 0;
}
--i1; --i2; ++j;
}
while( i1 >= 0 )
{
tmp = str1[i1]-'0'-carry;
if( tmp < 0 )
{
str3[j] = tmp+10+'0'; carry = 1;
}
else
{
str3[j] = tmp+'0'; carry = 0;
}
--i1; ++j;
}
--j;
while( str3[j] == '0' && j > 0 ) --j;
str3[++j] = '\0';
for( i=0, --j; i < j; ++i, --j )
{
ch = str3; str3 = str3[j]; str3[j] = ch;
}
}
乘法：
void Mul(char *str1, char *str2, char *str3)
{
int i, j, i1, i2, tmp, carry, jj;
int len1 = strlen(str1), len2 = strlen(str2);
char ch;
jj = carry = 0;
for( i1=len1-1; i1 >= 0; --i1 )
{
j = jj;
for( i2=len2-1; i2 >= 0; --i2, ++j )
{
tmp =
(str3[j]-'0')+(str1[i1]-'0')*(str2[i2]-'0')+carry;
if( tmp > 9 )
{
carry = tmp/10; str3[j] = tmp%10+'0';
}
else
{
str3[j] = tmp+'0'; carry = 0;
}
}
if( carry )
{
str3[j] = carry+'0'; carry = 0; ++j;
}
++jj;
}
--j;
while( str3[j] == '0' && j > 0 ) --j;
str3[++j] = '\0';
for( i=0, --j; i < j; ++i, --j )
{
{
ch = str3; str3 = str3[j]; str3[j] = ch;
}
}
除法 ：
void Div(char *str1, char *str2, char *str3)
{
int i1, i2, i, j, jj, tag, carry, cf , c[MAXSIZE];
int len1 = strlen(str1), len2 = strlen(str2), lend;
char d[MAXSIZE];
memset(c, 0, sizeof(c));
memcpy(d, str1, len2);
lend = len2; j = 0;
for( i1=len2-1; i1 < len1; ++i1 )
{
if( lend < len2 )
{
d[lend] = str1[i1+1]; c[j] = 0;
++j; ++lend;
}
else if( lend == len2 )
{
jj = 1;
for( i=0; i < lend; ++i )
{
if( d > str2 ) break;
else if( d < str2 )
{
jj = 0; break;
}
}
if( jj == 0 )
{
d[lend] = str1[i1+1]; c[j] = 0;
++j; ++lend;
continue;
}
}
if( jj==1 || lend > len2 ){
cf = jj=0;
while( d[jj] <= '0' && jj < lend ) ++jj;
if( lend-jj > len2 ) cf = 1;
else if( lend-jj < len2 ) cf = 0;
else
{
i2 = 0; cf = 1;
for( i=jj; i < lend; ++i )
{
if( d < str2[i2] )
{
cf = 0; break;
}
else if( d > str2[i2] )
{
break;
}
++i2;
}
}//else
while( cf )
{
i2 = len2-1; cf = 0;
for( i=lend-1; i >= lend-len2; --i )
{
d = d-str2[i2]+'0';
if( d < '0' )
{
d = d+10; carry = 1;
--d[i-1];
}
else carry = 0;
--i2;
}
++c[j]; jj=0;
while( d[jj] <= '0' && jj < lend ) ++jj;
if( lend-jj > len2 ) cf = 1;
else if( lend-jj < len2 ) cf = 0;
else
{
i2 = 0; cf = 1;
for( i=jj; i < lend; ++i )
{
if( d < str2[i2] )
{
cf = 0; break;
}
else if( d > str2[i2] )
{
break;
}
++i2;
}
}//else
}//while
jj = 0;
while( d[jj] <= '0' && jj < lend ) ++jj;
for( i=0;i < lend-jj; ++i ) d = d[i+jj];
d = str1[i1+1]; lend = i+1;
++j;
}//else
}//for
i = tag = 0;
while( c == 0 ) ++i;
for( ; i < j; ++i, ++tag ) str3[tag] = c+'0';
str3[tag] = '\0';
} 