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java indexof()简单字符查找实例
int indexof(string ch);
就是查找字符/字符串ch在index以后的位置,如果没有找到返回-1;index可以有可以没有，没有时默认为0。
eg: string str="liuzheliuxing";
system.out.println((int)"i") // i的ascii
system.out.println(str.indexof(105,0)); // i的ascii是105
结果是：1
eg: string str="liuzheliuxing";
system.out.println(str.indexof("i",2));
结果：7
应用：判断参数是不是数字类型
public boolean isnumber(string str){
string number="103194825611";
for (int i = 0; i< str.length(); i++) {
if(number.indexof(str.charat(i)) == -1) {
return false;
}
}
return true;
}
看个实例
public class mainclass
{
public static void main( string args[] )
{
string letters = "abcdefghijklmabcdefghijklm";
system.out.printf(
""c" is located at index %dn", letters.indexof( "c" ) );
system.out.printf(
""a" is located at index %dn", letters.indexof( "a", 1 ) );
system.out.printf(
""$" is located at index %dnn", letters.indexof( "$" ) );}
}