C语言程序设计 课件 ch4.pptx

选择结构;关系运算符及其表达式;关系运算符;示例1;逻辑运算符及其表达式;逻辑运算符;示例2;短路求值;综合示例;if语句;简单if语句;综合实例1;#include stdio.hint main(){ int a, b, t; scanf(%d%d, a, b); if(a b) { t = a; a = b; b = t; } printf(%d %d, a, b); return 0;};if-else语句;综合实例2;#include stdio.hint main(){ int score; printf(请输入学生成绩：); scanf(%d, score); if(score = 60) { printf(该学生成绩及格！\n); } else { printf(该学生成绩不及格！\n); } return 0;};if-else-if语句;if-else-if语句（续）;综合实例3;#include stdio.hint main(){ double x, y; scanf(%lf, x); if(x 0.5 || x = 7.5) { printf(x值超出范围！\n); } else if(x 1.5) { y = sin(x); printf(sin(%lf)=%lf\n, x, y); };条件运算符及其表达式;条件运算符与表达式;综合实例4;#include stdio.hint main(){ int a, b, maxnum; scanf(%d%d, a, b); maxnum = a b ? a : b; /*因条件运算符优先级比赋值运算符高，故可不加括号*/ printf(%d\n, maxnum); return 0;};switch语句;switch语句;注意事项;综合实例5;#include stdio.hint main(){ int n; scanf(%d, n); switch (n) { case 7: printf(*******\n); case 6: printf(******\n); case 5: printf(*****\n); case 4: printf(****\n); case 3: printf(***\n); case 2: printf(**\n); case 1: printf(*\n); } return 0;};break语句;综合实例6;#include stdio.hint main(){ char grade; scanf(%c, grade); switch (grade) { case A: printf(85~100\n); break; case B: printf(70~84\n); break; case C: printf(60~69\n); break; case D: printf(60\n); break; default: printf(error\n); } return 0;};说明;综合实例7;#include stdio.hint main(){ float score; scanf(%f, score); switch ((int)(score / 10)) { case 10: case 9: printf(A\n); break; case 8: printf(B\n); break; case 7: printf(C\n); break; case 6: printf(D\n); break; default: printf(E\n); } return 0;};选择的嵌套;嵌套选择;比较;测试;综合实例8;#include stdio.hint main(){