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1、第第6 6章章 循环控制结构循环控制结构哈尔滨工业大学计算机科学与技术学院*2/63本章学习内容本章学习内容 计数控制的循环计数控制的循环 条件控制的循环条件控制的循环 forfor语句，语句，whilewhile语句，语句，do-whiledo-while语句语句 continuecontinue语句，语句，breakbreak语句语句 嵌套循环嵌套循环 结构化程序设计的基本思想结构化程序设计的基本思想 程序调试与排错程序调试与排错*3/63Example:Example:如何确定程 序的输输入 和输输出呢?Draw a flowchart for the following problem
2、: 读读入5个整数，计计算并显显示它们们的和.Input : 5 个整数n1, n2, n3, n4, n5 Output: n1, n2, n3, n4, n5的和Input example: 2 3 4 5 6Output example: 20问题的提出问题的提出*4/63Input n1Input n2Input n3input n4input n5output sumsum n1+n2+n3+n4+n52 2n1Assume input example:2 3 4 5 63 3n24 4n35 5n46 6n52020sumend使用了6个不同的变变量start问题的提出问题的提出*
3、5/636.16.1循环控制结构与循环语句循环控制结构与循环语句标记标记标记标记 控制控制 Sentinel Sentinel ControlledControlled计计计计数控制数控制 Counter ControlledCounter Controlled 1, 2, 3, 4, , 4, 3, 2, 1条件控制条件控制 Condition Condition ControlledControlled如何对循环进行控制呢如何对循环进行控制呢? ?*6/63counter 1, sum 0counter#include RAND_MAXRAND_MAX在在stdlib.hstdlib.h中
4、定义，不大于双字节整数中定义，不大于双字节整数 的最大值的最大值32767 32767 产生产生0,b-1 0,b-1 之间的随机数之间的随机数 magic = rand()%b;magic = rand()%b;产生产生a,a+b-1 a,a+b-1 之间的随机数之间的随机数 magic = rand()%b + a; magic = rand()%b + a; *32/63# #includeinclude # #includeinclude main()main() intint magic; /* magic; /*计算机计算机“ “想想“ “的数的数* */ / intint gue
5、ss; /* guess; /*人猜的数人猜的数* */ /magic = rand()%100 + 1; magic = rand()%100 + 1; /*“/*“想想” ”一个一个11，100100之间的数之间的数magic*/magic*/printf(“Please guess a magic number:“);printf(“Please guess a magic number:“); scanf(“%d“, scanf(“%d“, ifif (guess magic) (guess magic) printf(“Wrong! Too high!n“); printf(“Wro
6、ng! Too high!n“); else ifelse if (guess # #includeinclude main()main() intint magic; magic; intint guess; guess; intint counter; counter; /*/*记录人猜次数的计数器变量记录人猜次数的计数器变量* */ /magic = rand() % 100 + 1; magic = rand() % 100 + 1; counter = 0; counter = 0; /*/*计数器变量计数器变量countcount初始化为初始化为0*/0*/ dodo printf
7、(“Please guess a magic number:“);printf(“Please guess a magic number:“); scanf(“%d“, scanf(“%d“, counter +; counter +; /*/*计数器变量计数器变量countcount加加1*/1*/ ifif (guess magic) (guess magic) printf(“Wrong! Too high!n“); printf(“Wrong! Too high!n“); else ifelse if (guess # #includeinclude main()main() inti
8、nt magic; magic; intint guess; guess; intint counter; /*counter; /*记录人猜次数的计数器变量记录人猜次数的计数器变量* */ /unsigned int unsigned int seed;seed;printf(“Please enter seed:“);printf(“Please enter seed:“); scanf(“%u“, scanf(“%u“, srand(seed);srand(seed); magic = rand() % 100 + 1; magic = rand() % 100 + 1; counter
9、 = 0; /*counter = 0; /*计数器变量计数器变量countcount初始化为初始化为0*/0*/ dodo printf(“Please guess a magic number:“);printf(“Please guess a magic number:“); scanf(“%d“, scanf(“%d“, counter +; /*counter +; /*计数器变量计数器变量countcount加加1*/1*/ ifif (guess magic) (guess magic) printf(“Wrong! Too high!n“); printf(“Wrong! To
10、o high!n“); else ifelse if (guess #include srand(time(NULL); srand(time(NULL); magic = rand() % 100 + 1; magic = rand() % 100 + 1; 函数函数time()time()能为程序员提供代表时间的字符串，能为程序员提供代表时间的字符串， 使用使用NULLNULL作为函数参数，使其不具备此功能作为函数参数，使其不具备此功能*37/63# #includeinclude # #includeinclude #include #include main()main() intin
11、t magic; magic; intint guess; guess; intint counter; /*counter; /*记录人猜次数的计数器变量记录人猜次数的计数器变量* */ /srand(time(NULL); srand(time(NULL); magic = rand() % 100 + 1; magic = rand() % 100 + 1; counter = 0; /*counter = 0; /*计数器变量计数器变量countcount初始化为初始化为0*/0*/ dodo printf(“Please guess a magic number:“);printf(
12、“Please guess a magic number:“); scanf(“%d“, scanf(“%d“, counter +; /*counter +; /*计数器变量计数器变量countcount加加1*/1*/ ifif (guess magic) (guess magic) printf(“Wrong! Too high!n“); printf(“Wrong! Too high!n“); else ifelse if (guess # #includeinclude # #includeinclude main()main() intint magic; magic; intin
13、t guess; guess; intint counter; /*counter; /*记录人猜次数的计数器变量记录人猜次数的计数器变量* */ /srand(time(NULL); srand(time(NULL); magic = rand() % 100 + 1;magic = rand() % 100 + 1;counter = 0; /*counter = 0; /*计数器变量计数器变量countcount初始化为初始化为0*/0*/ dodo printf(“Please guess a magic number:“);printf(“Please guess a magic number:“); scanf(“%d“, scanf(“%d“, counter +; /*counter +; /*计数器变量计数器变量countcount加加1*/1*/ ifif (guess magic
