c语言大数位加法,求用C编个大数加减法运算程序

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只写过加法的，杭电的A + B Problem (II)(AC)：

#include

#include

#include

#define N 3000

int main(void)

{

int n, i, j, k, p, q, a, b, t, up;

char s[N];

scanf("%d ", &n);

for (i = 0; i < n; i++) {

int sum[N] = {0};

printf("Case %d:n", i + 1);

fgets(s, N, stdin);

for (t = q = strlen(s) - 2; isdigit(s[t]); t--)

;

for (p = t - 1, up = j = 0; p >= 0 || isdigit(s[q]);) {

a = p >= 0 ? s[p--] - '0' : 0;

b = isdigit(s[q]) ? s[q--] - '0' : 0;

t = a + b + up;

sum[j++] = t % 10;

up = t / 10;

}

if (up) sum[j] = up;

for (k = 0; isdigit(s[k]);) printf("%d", s[k++]-'0');

for (printf(" + "), k++; k < strlen(s) - 1;) printf("%d", s[k++]-'0');

for (printf(" = "), k = N-1; sum[k] == 0; k--) ;

for (; k >= 0; k--) printf("%d", sum[k]);

printf("n");

if (i != n-1) printf("n");

}

return 0;

}

供参考……减法应该类似……不难写出。