我刚刚发现还有一个代码功能，就把代码复制一遍，又在第三楼发了一遍
#include <stdio.h>
#include <string.h>
int main()
{
    char str1[1024],str2[1024],c[1025];
    int n1 = 0;
    int n2 = 0;
    int i,j,k,n,t1,t2;
    k = 0;
    j = 0;
    scanf("%d", &n);
   
    while (++j)
    {
        if(j > n)
            break;
        scanf("%s%s", str1, str2);
        t1 = n1 = strlen(str1)-1;
        t2 = n2 = strlen(str2)-1;
        
        for(i=0; i<=n1||i<=n2; i++)
        {
            if(i > n1)
                k = str2[t2--] - '0' + k;
            else if(i > n2)
                    k = str1[t1--] - '0' + k;
            else
                k = str1[t1--]+str2[t2--]-2*'0' + k;
            if(k>=10)
            {
                c[i] = k%10 + '0';
                k = 1;
            }
            else
            {
                c[i] = k + '0';
                k = 0;
            }
            
        }
        if(k == 1)
        {
            c[i] = 1 + '0';
            c[i+1] = 0;
        }
        else
        {
            c[i] = 0;
        }
        
        printf("Case %d:\n", j);
        printf("%s + %s = ", str1, str2);
        while(i>=0)
        {
            printf("%c", c[i]);
            i--;
        }
        if(j != n-1)
            printf("\n\n");
    }
   
    return 0;
}

[此贴子已经被作者于2016-2-7 18:24编辑过]

#include <stdio.h>
#include <string.h>
int main()
{
    char str1[1024],str2[1024],c[1025];
    int n1 = 0;
    int n2 = 0;
    int i,j,k,n,t1,t2;
    k = 0;
    j = 0;
    scanf("%d", &n);
    
    while (++j)
    {
        if(j > n)
            break;
        scanf("%s%s", str1, str2);
        t1 = n1 = strlen(str1)-1;
        t2 = n2 = strlen(str2)-1;
        
        for(i=0; i<=n1||i<=n2; i++) 
        {
            if(i > n1)
                k = str2[t2--] - '0' + k;
            else if(i > n2)
                    k = str1[t1--] - '0' + k;
            else
                k = str1[t1--]+str2[t2--]-2*'0' + k;
            if(k>=10)
            {
                c[i] = k%10 + '0';
                k = 1;
            }
            else
            {
                c[i] = k + '0';
                k = 0;
            }
            
        }
        if(k == 1)
        {
            c[i] = 1 + '0';
            c[i+1] = 0;
        }
        else
        {
            c[i] = 0;
        }
        
        printf("Case %d:\n", j);
        printf("%s + %s = ", str1, str2);
        while(i>=0)
        {
            printf("%c", c[i]);
            i--;
        }
        if(j != n-1)
            printf("\n\n");
    }
    
    return 0;
}

目前看到几个错误：
1、进位k未清零，会导致在计算第二个数时计算进去。
2、显示格式错误
3、Case num:,题意要求从1开始计数

//这样应该可以
#include <stdio.h>
#include <string.h>
int main()
{
    char str1[1000],str2[1000],c[1001];
    int n1 = 0;
    int n2 = 0;
    int i,j,k,n,t1,t2;
    k = 0;
    j = 0;
    scanf("%d", &n);
   
    while (++j)
    {
        if(j > n)
            break;
        scanf("%s%s", str1, str2);
        t1 = n1 = strlen(str1)-1;
        t2 = n2 = strlen(str2)-1;
        for(i=0,k=0; i<=n1||i<=n2; i++)
        {
            if(i > n1)
                k = str2[t2--] - '0' + k;
            else if(i > n2)
                    k = str1[t1--] - '0' + k;
            else
                k = str1[t1--]+str2[t2--]-2*'0' + k;
            if(k>=10)
            {
                c[i] = k%10 + '0';
                k = 1;
            }
            else
            {
                c[i] = k + '0';
                k = 0;
            }
            
        }
        if(k == 1)
        {
            c[i] = 1 + '0';
            c[i+1] = 0;
        }
        else
        {
            c[i] = 0;
            i--;
        }
        printf("Case %d:\n", j);
        printf("%s + %s = ", str1, str2);
        while(i>=0)
        {
            printf("%c", c[i]);
            i--;
        }
        printf("\n");
        if(j<n)printf("\n");
    }
   
    return 0;
}

好的，成功AC，谢谢，AC图一张