Question

当我尝试在flex程序中打印字符串（cout）时，程序崩溃。我的.l文件看起来像这样：

%{
    #include <iostream>
    #include <string>

    using namespace std;
%}

%option noyywrap

%%
.   {string str = "hi"; cout << str;}
%%

int main(){
    yylex();

    return 0;
}

我使用g ++编译生成的文件。我的flex版本是2.5.35。

当我简单地写cout << "hi";时，程序不会崩溃。

我做错了什么？

Answer 1

它似乎适用于flex版本2.5.39。

您可以使用g ++ -E预处理生成的文件并查看输出以查看是否有

的翻译

                server <- function(input, output) {

             output$plot2 = renderPlot({
           database = odbcConnect("database")
              start_date = print(input$dates[1])
              end_date = print(input$dates[2])
              my_query="SELECT 
              top 30
                        convert(char(10),datetime,121) as date, 
                         cast(start_destination as varchar(3)) 
                        + (',') + cast(final_destination as varchar(3)) as combo,
                           count(cast(start_destination as varchar(3)) 
                           + (',') + cast(final_destination as varchar(3))) as volume  
                          FROM
                          trips
                              WHERE 
                           datetime >= DATE1 AND
                           datetime < DATE2
                            GROUP BY
                             cast(start_destination as varchar(3)) 
                           + (',') + cast(final_destination as varchar(3)),
                             convert(char(10),datetime,121);"

                my_query <- sub("DATE1",as.Date(start_date),my_query);
              my_query <- sub("DATE2",as.Date(end_date),my_query)
             sql = sqlQuery(database, paste(my_query))
            sql = data.frame(sql, do.call(rbind, str_split(sql$combo, ',')))
           colnames(sql)[colnames(sql)=="X1"] <- "From"
           colnames(sql)[colnames(sql)=="X2"] <- "To"
           sql = sql[,c(4,5,3)]
            sql = sql[order(sql$volume, decreasing = T),]
            chordDiagram(sql)
             circos.clear()
               })


             }


             shinyApp(ui, server)

没有改变。

flex cout字符串崩溃

1 个答案: