缘由https://bbs.csdn.net/topics/398165677

	//字符串指定位置倒序输出缘由https://bbs.csdn.net/topics/398165677
	char aa[] = "abcABCabc\n";
	int a = 3, b = 5, c = 0, d = b;
	while (aa[c] != '\n')if (c < a || c > b)cout << aa[c++]; else if(d >= a) cout << aa[d--], ++c;

	char aa[] = "abcABCabc\n";
	string asa = "";
	cin >> asa; asa += "\n";
	int a = 4, b = 7, c = 0, d = b;
	cin >> a >> b; d = b;
	while (asa[c] != '\n')if (c < a || c > b)cout << asa[c++]; else if (d >= a) cout << asa[d--], ++c;

	char aa[] = "abcABCabc\n", jh;
	string asa = "";
	cin >> asa; asa += "\n";
	int a = 4, b = 7, c = 0, d = b;
	cin >> a >> b; d = b;
	//while (asa[c] != '\n')if (c < a || c > b)cout << asa[c++]; else if (d >= a) cout << asa[d--], ++c;
	while (a != b)jh = asa[a], asa[a] = asa[b], asa[b] = jh, ++a, --b;
	cout << asa;