int main(){ int oddsum(int num);int n;printf("请输入一个正整数:\n");scanf("%d",&n);printf("1到%d之间的所有奇数之和:%d\n",n,oddsum(n));return 0;} int oddsum(int num){ if(num%2==0)return (1+num-1)*(num/2)/2;else return (1+num)*((num+1)/2)/2;}...