read one system Excel file 
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library(openxlsx)
x <- system.file("extdata", "readTest.xlsx", package ="openxlsx")
x
[1] "C:/Users/Paul Yan/AppData/Local/R/win-library/4.3/openxlsx/extdata/readTest.xlsx"

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Sheet names
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library(openxlsx)

# infile<- "path/to/your/excel_file.xlsx"
infile <- system.file("extdata" ,"readTest.xlsx",package ="openxlsx")
sheet_names <- getSheetNames(infile)

print(sheet_names)
 [1] "Sheet1"  "Sheet2"  "Sheet 3" "Sheet 4" "Sheet 5" "Sheet 6" "1"      
 [8] "11"      "111"     "1111"    "11111"   "111111" 

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Reading different sheets
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library(openxlsx)

infile <- system.file(" extdata" , " readTest.xlsx" , package = " openxlsx" )

df1 <- read.xlsx(xlsxFile = xlsxFile, sheet = 1, skipEmptyRows = FALSE)
head(df1)

df2 <- read.xlsx(xlsxFile = xlsxFile, sheet = 3, skipEmptyRows = TRUE)
df2$Date <- convertToDate(df2$Date)
head(df2)

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all system Excel files
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loc<-'http://datayyy.com/data_excel/'
x<-readLines(loc)
x2<-x[grep(".xlsx",x)]
x3<-sub(".xlsx.*",".xlsx",x2)
x4<-sub(".*sort=\"","",x3)

> x4
 [1] "amexcap.xlsx"              "benford.xlsx"              "bs_ibm.xlsx"              
 [4] "chickeneggs.xlsx"          "countryrisk2.xlsx"         "cpimonthly_cpiaucsl.xlsx" 
 [7] "datacase5.xlsx"            "datamonthly.xlsx"          "dollarindexweights.xlsx"  
[10] "eventstudy.xlsx"           "ex16_4.xlsx"               "ex2_canus_usuk.xlsx"      
[13] "exam2021f.xlsx"            "excaus_exuseu.xlsx"        "exhibit16_4.xlsx"         
[16] "f311hw3q4.xlsx"            "ff3_ibm5years.xlsx"        "ff3_ibmmonthly.xlsx"      
[19] "ff3monthly.xlsx"           "fin508datacase1.xlsx"      "final2.xlsx"              
[22] "gands.xlsx"                "googlescholargeneseo.xlsx" "gs2schools.xlsx"          
[25] "ibm.xlsx"                  "ibmdaily.xlsx"             "ibmis_bs.xlsx"            
[28] "ibmmonthly.xlsx"           "is_ibm.xlsx"               "jnj.xlsx"                 
[31] "kuiper.xlsx"               "multidata3.xlsx"           "nstock_stdport.xlsx"      
[34] "nysecap.xlsx"              "nyselisting.xlsx"          "sp500annual.xlsx"         
[37] "sp500constituents.xlsx"    "sp500monthly.xlsx"         "wmtmonthly.xlsx"          

some issues with capitalization amexcap.xlsx should be amexCap.xlsx
  check http://datayyy.com/data_excel/list.txt

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