简单 - if 语句if - else 语句嵌套 - if else 语句else – ifladderswitch 语句简单 – if 语句“if”关键字是用于在逻辑条件为真时执行一组语句。
语法if (condition){ statement (s)}
示例 以下示例检查数字是否大于 50。
#include<stdio.h>main (){ int a; printf (“enter any number:
”); scanf (“%d”, &a); if (a>50) printf (“%d is greater than 50”, a);}
输出1) enter any number: 6060 is greater than 50 .2) enter any number 20no output
if else语句if else语句接受true或false条件。
语法if (condition){ true block statement(s)}else{ false block statement(s)}
流程图
示例以下是检查奇偶数的程序 −
#include<stdio.h>main (){ int n; printf (“enter any number:
”); scanf (“%d”, &n); if (n%2 ==0) printf (“%d is even number”, n); else printf( “%d is odd number”, n);}
输出1) enter any number: 1010 is even number
嵌套的 if - else 语句这里的“if”被放置在另一个 if（或）else 中 -
语法if (condition1){ if (condition2) stmt1; else stmt2; } else{ if (condition3) stmt3; else stmt4; }
流程图
示例以下示例是打印给定数字中最大的3个数字。
#include<stdio.h>main (){ int a,b,c; printf (“enter 3 numbers”); scanf (“%d%d%d”, &a, &b, &c); if (a>b){ if (a>c) printf (“%d is largest”, a); else printf (“%d is largest”, c); } else { if (b>c) printf (“%d is largest”, b); else printf (“%d is largest”, c); }}
输出enter 3 numbers = 10 20 3030 is largest
else – if ladder它是一个多路决策条件。
syntaxif (condition1) stmt1;else if (condition2) stmt2; - - - - - - - - - -else if (condition n) stmt n;else stmt x;
流程图
示例以下示例求二次方程的根 -
#include <math.h>main (){ int a,b,c,d; float r1, r2 printf ("enter the values a b c"); scanf (“%d%d%d”, &a, &b, &c); d= b*b – 4*a*c ; if (d>0){ r1 = (-b+sqrt(d)) / (2*a); r2 = (-b-sqrt(d)) / (2*a); printf (“root1 ,root2 =%f%f”, r1, r2); } else if (d== 0){ r1 = -b / (2*a); r2 = -b/ (2*a); printf (“root1, root2 = %f%f”, r1, r2); } else printf ("roots are imaginary”);}
输出1) enter the values of a b c : 1 4 3root 1 = -1root 2 = -3
switch 语句它有助于从多个决策中选择一个。
语法switch (expression){ case value1 : stmt1; break; case value2 : stmt2; break; - - - - - - default : stmt – x;}
语法
示例#include<stdio.h>main (){ int n; printf (“enter a number”); scanf (“%d”, &n); switch (n){ case 0 : printf (“zero”) break; case 1 : printf (‘one”); break; default : printf (‘wrong choice”); }}
输出enter a number1one
以上就是使用流程图和程序来描述c语言中的决策概念的详细内容。