给一个n位字符串，按顺序从1开始到最大N输出，

bool increment(char *num) {

bool overflow = false;

int jw = 0;//进位否

int n = strlen(num);

for(int i = n - 1; i >= 0; --i) {

int nsum = num[i] - '0' + jw;

if(i = n - 1)

++nsum;

if(nsum >= 10) {

if(i == 0)

overflow = true;

else {

jw = 1;

nsum -= 10;

num[i] = '0' + nsum;

}

}

else {

num[i] = '0' + nsum;

break;

}

}

return overflow;

};